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Discussion Starter · #1 · (Edited)
Have in storage a '98 stick-n-staple Winnebago RV with a clean low mile 5.9 12-Valve mated to an Alison 6 speed "world" transmission. This powerplant and drivetrain only have 42,000 on the clock. Very clean, and running perfect. Got the RV for 6k.

Today I found an old MAC tool guy truck. Grumman-Olson all aluminum body, built on a GMC P6T040 chassis, 7'5"ft ceiling height, rolling on 22.5 rubber, it's a big ass van. Makes those old Frito trucks look very small... but its got a carb, 馃あ 427 big block GM 7.0l v8 and an Allison 4spd. Boo!

So my thinking is pull that just broke in 5.9 motor and trans from the stick and staple RV that is starting to melt away around a perfectly running Cummins, and re-power the forever truck with the forever engine and trans. Find a home for the big block V8 with some Hot Rod Tod.
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Anyone know about pulling a 5.9 that is in a "Pusher" configuration?

Thanks for your time and priceless collective genius.

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Since you've got both vehicles complete you are worlds ahead of most people. Is the 6bt in the RV the P7100 injection pump or is it a 24 valve ISB common rail. Either can work but pure mechanical 6bt's offer fewer potential headaches. Do you know what transmission is in the RV. I suspect it's an Allison 3060 which is a super strong 6 speed with double overdrives. Those were also found in medium duty trucks. Transmission weighs over 500 lbs. The HD delivery vans came with the 6bt so you should be able to work out all the details. Fun part will be wrestling that 3/4 tons+ of engine and transmission into the van. Might be easier to lift the body off the chassis. You'll have to double check things like turbo clearance to the van engine compartment. Those may have had a different exhaust manifold but all depends on what style is on the engine, Those delivery trucks have wider engine compartments than regular passenger vans so you'll probably be OK. Should be an interesting swap.
 

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Discussion Starter · #3 · (Edited)
Since you've got both vehicles complete you are worlds ahead of most people. Is the 6bt in the RV the P7100 injection pump or is it a 24 valve ISB common rail. Either can work but pure mechanical 6bt's offer fewer potential headaches. Do you know what transmission is in the RV. I suspect it's an Allison 3060 which is a super strong 6 speed with double overdrives. Those were also found in medium duty trucks. Transmission weighs over 500 lbs. The HD delivery vans came with the 6bt so you should be able to work out all the details. Fun part will be wrestling that 3/4 tons+ of engine and transmission into the van. Might be easier to lift the body off the chassis. You'll have to double check things like turbo clearance to the van engine compartment. Those may have had a different exhaust manifold but all depends on what style is on the engine, Those delivery trucks have wider engine compartments than regular passenger vans so you'll probably be OK. Should be an interesting swap.
Motor has a manual inline Bosch pump!
Allison is a 3060!

There is no lifting the body off the chassis. That would be a fools endeavor. But the whole front of the van unbolts, and the engine bay holds a 427 big block with plenty of room. Getting the 6BT and Allison in there will be a front load with a hoist or possibly I'll fab up a cradle that will allow me to roll it into place and use hydraulic bottles to lift it into place.

Most of the stuff I need is there between the two rigs. There will be lots of parts left over.


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The Chevy P6T has disk brakes all around and hydro boost. Love that. System is shared with the power steering. On the maiden voyage one of the rear calipers seized and so had to have the truck towed. That's what happens when stuff sits unused. This truck had been sitting since 2008.

Damn big truck. Drives easy though. Will be awesome with that Cummins and the 6speed Allison!
 

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Discussion Starter · #5 · (Edited)
So engine swap aside. What are you going to do with this huge van? RV or workshop or what?
Better than an RV, much better than a Bus. Bigger than a Sprinter, but not too big. 28鈥 bumper to bumper. Grumman body will literally last a lifetime. This is the 5th Grumman for me, and the biggest by far. The 7鈥 interior height is F'n awesome. I'm 6'鈦粹.
Plus, He already has generator, propane, onboard air, lift gate, 120 wired, two AC units. Will be used for whatever needs fit it's stature and accomodations. Race outings, misc travel, mobile work, hauling motorcycles or pulling a trailer. It's a great machine! Has adjustable air ride height! PO didn't know if it worked or not. It's working! Just a damn big awesome truck. Very well cared for by the original owner, then the next guy just let it sit in his driveway for 14 years. Fortunately not too much is wrong with the chassis. GM parts are abundant and easy to find and cheap.
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Excuse the mess! This was the view tonight after he came back from the truck shop where they fixed the stuck rear caliper. Had them replace both rear calipers and turn the rotors also. Dove right into demolition of the old MAC tool salesman interior. Look at all that peg board. I'll take it down to the bare Aluminum, polyfoam insulate and frame the new interior amenities.
 

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Those vans probably came with the Cummins as an option. Being a Chevy model that may not be true but won't hurt to check. Might be able to buy engine mounts off the rack if they still have them. Do you know the CPL number of the Cummins? There were various power levels with the P pump engines. The king of the hill was the CPL 1553 which is 230 HP and over 600 lb ft of torque. That was the most powerful 6bt 12 valve model used in road vehicles. Some of the marine versions went up to a tad over 400 HP but those are a different animal. You will want to add a few gauges to the dash. Tach, boost, and egt would be the basics. Might have those in the RV that you can salvage. Might have one for transmission temp in the RV as well. Can't have too many gauges.
 

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Discussion Starter · #7 ·
Those vans probably came with the Cummins as an option. Being a Chevy model that may not be true but won't hurt to check. Might be able to buy engine mounts off the rack if they still have them. Do you know the CPL number of the Cummins? There were various power levels with the P pump engines. The king of the hill was the CPL 1553 which is 230 HP and over 600 lb ft of torque. That was the most powerful 6bt 12 valve model used in road vehicles. Some of the marine versions went up to a tad over 400 HP but those are a different animal. You will want to add a few gauges to the dash. Tach, boost, and egt would be the basics. Might have those in the RV that you can salvage. Might have one for transmission temp in the RV as well. Can't have too many gauges.
I do not know the CPL number, and I will need to do a little bit of googling to find out where I can find this number. I'll get it and report back.

Yes somebody else I was speaking to in person had mentioned that I may be able to find off the shelf mounts for both the Allison and the Cummins. It's a 1988 I think that the chassis designator is P60T. Or P6T. How goddamn awesome would it be if I could find off the shelf parts for mounting the swapped power plant! Fingers crossed.
 

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Discussion Starter · #9 ·
Is your pusher engine in front of or behind the trans., if behind, do you have to change?

Ed in CO
Engine/Tans is mounted behind rear axle. Backwards.
The answer, I do not know yet. I assume that the reverse gearing is in the rear differential of the Spartan motorhome chassis. Hopefully that's the case and not something more complex like a Cummins that is set up to run CCW direction.
 

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Sounds as if you have a solid plan. I recently demolished a pusher class A motorhome. If you're patient, it can fit in a dumpster. Now I have a very low mileage 12V Cummins. The flip for the drive is achieved by turning the rear axle upside down. Mine has a Dana 80, upside down and backwards. Unfortunately the Allison is non overdrive so although it works well with its diesel specific TC it's going to have to go.

Just be aware that stuff is in different places on pushers. The very large radiator is on the wrong side of the intercooler for a puller, obviously the fan would have to be swapped. The starter is on the exhaust side so that's not ideal for firewall clearance but that's all going on mine. Stuff to figure out.
Plus I have to remove the air compressor and get a new mount for the hydraulic pump which I want to keep to run hydro boost.
 

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Been there, Kinda!
The 12 valve will fit in the Grumman just fine. Though the 3060 & Cummins will be heavy, so be sure to use the largest capacity engine hoist you can find. On my swap I found out the hard way that fact because my lift crane was rated at 2K and it bend the legs a little.
The 3060 is a fine non electronic transmission that should serve you well.

Here's part of my experience on my swap.
My Coach is a FERD (1989 Fleetwood Limited Class 37' A RV) and I swapped out the EFI 460 / C6 Tranny to a 1998 12 Valve Cummins with an AT542 at first. I now have a World 1000 5 speed behind the Cummins.
As for the pusher rotation, don't worry about it. It will turn just right I'm told. Was originally going to source a pusher drivetrain for my FERD, but then ran across a killer deal on the 12 valve.
Just remember to have lots of patience, because this will be like building a full size battleship in a beer bottle.
Your Grumman may be a lot easier since your dog house is a lot bigger than mine.

The engine mounts should work. Maybe need a little modfying. I used the Cummins mounts in the Ford Saddles. (My brand of Coach could be had with a Cummins motor, so the John Deere Frame was built to accomodate several different engine combos. Your Gummuns came with Cummins engines I know for a fact.) And you can always add a front mount to the engine like I did to simplify things. Depending on what you plan to do, you may want to consider swapping the rear ends while you're at it because it's geared for that engine tranny combo. I had to regear my Dana 70 from 4:88's to 3:56. & I added Limited Slip in there too!
Wiring will be simple easy with your engine/ tranny combo, since they are both Non electronic. The sending units should swap over between the engines. So the wiring for those will be a non issue. Just label them good because you might find the sending units are on the wrong side of the motor from the original engine.

I am currently bumping my 12 valve up to 400 HP and installed the AT1000 5 speed last month. BOught it before Allison came out with the 6 speed combo. But I could upgrade the thing to a 6 speed without replacing the transmission.

And this week while the Bosch P7100 injector pump is in for a rebuild I'm repllacing all the engines hoses, belts, seals, water pump, AC compressor, Expansion valve, RC drier, stuff. Remember it's a 33 year old drivetrain that's been sitting for years. So expect it to get expensive real quick. (If you do it right)

Our plan is to use my RV a lot pulling my 4X4 rock crawler, and don't want any surprises while out on the road, so I'm freshening up all I can get to. Remember, It's only money and you can always make more!
Plus it's easier to do it right the first time at your house, than it will be on the side of a busy highway.

My P pump "O" ring seals had hardened, and I found diesel fuel in the pump where oil should have been. NOcited several seal have dribbled while it sat for a few years. So they are all going to get replaced.
(Still using the OEM electric fuel pump in the fuel tank at the rear of the Big Girl. Going to install a pressure regualtor on it before the lift pump before I put it on the road.
So, since I was in the process of upgrading the govenor springs, the pressure valves, intalling the AFC Live in it I decided to just to it all right the first time and get it tuned by a Professional.
Had to strip off the entire left side of the engine to get the P Pump out the bottom, since the engine is basically under the floor. Being as how my Coach is a straight axle it wasn't that bad. I'm sure putting it back will be a bitch!
I'll be resealing the vacuum pump today and replacing the front crankshaft seal. And I forgot if i did the KDP on this engine, Sooooo I'll be checking it while in there.

I've got a lot going on with my swap, so I'm sure I've forgot some things to tell you to look out for. But if I think of any more I'll post up here. Oh and JSYK I originally did the gas to diesel swap in 2002. And now I'm refreshening it all over again, with a better transmission this time so the wife and I can do some Snowbirding and Off Roading we couldn't do when I was working.
Retired now 12 years, but have been batteling a long list of health issues for both of us for the last 7 years, I won't go into now. But just remember, your rigs are old, so treat them like they are going to leak everywhere and just do it right, and you'll be happy you did it. Seals are cheap if you do them at home!

I'll be happy to help if you have any issues. I'm in North Central Texas if you're close!
My original swap build was on this Forum when I first did it, but it's probably lost by now.
The picture below is off the Brochure, so my rig, (color and all) but not MY Rig!
 

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I knew I should have expounded on that statement when I wrote it. I tend to get wordy and want to spell everything, but tried to keep it short.
So My bad.
Yes the 3060 is an electronic transmission, but it has a Stand Alone Computer and requires a throttle position sensor and either a J1939 or the newer WTCIII or WTCIV to work behind a non electronic engine.
And yes, the Allison 1000 can be configured to work with a standalone TCM to work the same way. As mine is one. But mine only requires a TPS and a few other sensors to operate correctly.

My statement was more about the simplicity of the 3060 and didn't go into the Can Bus J1939 for engine data to the TCM. I'm Old school so the WTCIII etc I only know about and have never had to deal with that system.
But that is a whole nother can of worms. And I hear they are only rated for 275 horses stock and require an 18" #2 SAE bell housing.
They are monster transmissions. Had one in my work truck...

So you are correct!
I appreciate you pointing that out.
 

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Discussion Starter · #17 ·
Life has been busy, and I have not had a chance to get up to the storage place where I have that motorhome in waiting.

I recently demolished a pusher class A motorhome. If you're patient, it can fit in a dumpster.
Hah. That is encouraging. I'm going to pull the motor and trans, and strip the motorhome of any valuable bits, and then pay somebody to haul the rest of the hulking mass away. Time is more valuable to me than money.

Been there, Kinda!
The 12 valve will fit in the Grumman just fine.
Thanks for sharing your experience. Yeah. I know that the Cummins will fit in there with no issues, and they did come with this motor as an option. I'm hunting for mounts, so it will be as close to a bolt-in affair as possible. The Alison has an electronic box that controls shifting. I don't know much about what it requires to operate, so I'll have to do some research and educate myself on it at some point.

I'm going to leave the heavy duty rear end that is in the Grumman There. I care more about load capacity than going fast on the freeway. I can drive 55. No issues with that. Keep those RPMs low, and make time to travel slow. That's how I roll.

I'm up in Oregon outside of Portland, so I'm quite a ways away from Texas. Thanks for the offer to help though! Appreciate it.
 
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