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1989 Jeep Grand Wagoneer
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Ok here's my thoughts. The B series engine have a lower operateing rpm than the 440, therefore your going to need a overdrive somewhere in the drivetrain to be able to get down the road at a decent speed. Also just because a trans does good behind a monster gas moter dosent mean it can take the low speed torque of a diesel. But there are good Dodge trans that are fitted behind the 6B and changing the trans out is a good idea. What you need to find out is the gear ratio on the axle and find out how this works with what you have and make adjustment if necessary.
 

· Premium Member
1989 Jeep Grand Wagoneer
Joined
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2,990 Posts
Figured out I have a Dana 70 rearend with something lik 4.56 gearing. A friend suggested 3.73 gearing for the swap. My question is with a newer 24valve 6bt and overdrive auto tranny out of a Dodge 3500, Would I end up with the best mileage for the power in this 12,000 GVW Winnebago? I guess I need to find out what a Dodge M400 with a 6bt and auto tranny had in the rear end, eh? Or would whatever rearend gearing is in the 3500 be what I would want? :D
1st and 2nd gen Dodge CTD's get best fuel mileage below 2K rpm, 3rd gen moves this up a few hundred rpm, I'm not sure where the "power band" starts for a 3 gen, but you need to know that for setting up the optimum gearing. I would ask anyone that tows with a 24valve what they have.
I've towed 12K GCWR up and down the west coast with my 92 Dodge with just the stock 160 hp and it's not bad. I'm geared lower, I turn just over 2000 rpm at 65mph. My mileage sucks but I have the power to pull.
 
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