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Discussion Starter · #1 ·
I currently have a '90 gmc k1500 with 3.42 gears and 33" tires and a 350 TBI. I would like to know how the power of the 4bt compares with the 350. My guess is that it would feel stronger at low-rpm low-speed driving, but slower in full throttle? Its kind of an awkward question, but I am trying to decide if a 4BT would be enough power or I should get a 6BT. I am happy with the truck current power, but it takes forever to get to the power-band
 

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You didn't mention whether you have a 5 speed or auto. Mine is a 5 speed truck with the same gears and 265/75/16 tires, so you'd be geared slightly higher than I am. Can't comment on how life would be with the auto, but here are my observations based upon 60000 miles of driving my rig. Whether or not the power would be adequate depends entirely upon your expectations and intended use for the vehicle. I did my swap just for the sake of having a fullsize truck with a small diesel to use as a daily driver. I honestly expected it to be a slug, and would not have cared if it was as long as the mpg was good. It has not (and probably will not) make my goal of 30 mpg, but I can live with the 26 -28 that it does get. Concerning power, I was very pleasantly surprised. With a good tune up (setting timing, valve lash, etc.), and some basic AFC tweaks, the acceleration is comparable to the TBI 350, and the bottom end power comparison is absolutely no contest in favor of the 4BT. If towing or big power are of concern to you, then you'd probably be happier with the 6BT, but I would be apprehensive about putting one in a 1/2 ton. A fully dressed 6BT weighs in excess of 1200 lbs, which would, in my opinion, be excessive for the 1/2 ton front suspension components. Also, even a stock 6BT could easily exceed the torque handling capabilities of the 1/2 ton driveline.
 

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Discussion Starter · #3 ·
Which transmission do you have? I have a 700R4 now but will convert to standard shift. I plan to find a junkyard truck and take the clutch pedal and linkage. I would get the NV4500 but I would have different splines to my transfer case. Also did the 4BT you have come with a manual transmission? Would you recomend I look for a manual transmissoin 4BT or could I just find a flywheel somewere? Thanks
 

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My truck has the stock HM290 Getrag. The NVG4500 is the simpler option as using it in conjuction with the Dodge clutch/flywheel/bellhousing/adapter plate/input shaft will facilitate a vertical engine mounting and is pretty much a bolt-together installation. As the HM290's bellhousing is integral like an auto (not detachable), the only option there is to use the tilted GM adapter, which I had to untilt (that's another story) to get the engine vertical. My 4BT had an auto behind it as the overwhelming majority of takeout engines you will find do. Engine is the same regardless of trans mated to it, given the same CPL #. Good luck finding used a Cummins/GM manual flywheel. They're still available from Cummins, but pricey. If you're going to buy a trans anyway, I'd recommend going the NVG4500 route and using the Dodge stuff, as the Dodge setup is much easier to find.
 

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Discussion Starter · #5 ·
Ok, if I use the dodge setup - how do I attach it to my transfer case? I understand there is a different spline on the dodge output shaft? Is there a driver side drop dodge transfer case? Or can I buy an adaptor to go from dodge nv4500 to gm np241? Thanks for your help! I just bought a chainfall today
 

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Ok, if I use the dodge setup - how do I attach it to my transfer case? I understand there is a different spline on the dodge output shaft? Is there a driver side drop dodge transfer case? Or can I buy an adaptor to go from dodge nv4500 to gm np241? Thanks for your help! I just bought a chainfall today
If you get a 96 or newer GM nv4500 the dodge B/H will fit and also a dodge I/P shaft will fit right on. problem solved.

Gaza
 
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