Joe, that sounds like a great project. Did you know that General Motors actually made a 1-1/2 ton dually pickup in 1941? It used a 134-1/2" wheelbase and 9' bed.
As for your drivetrain dilemma.... You're not going to use that 70's motorhome rear end without replacing the gear oil are you? Well, just pop that cover off and count the gear teeth when you change the oil, and that way you can know for sure what you've got to work with. (assuming it's the Dana)
You asked about top speed and transmissions. Both of your transmissions are very-very likely 1:1 in top gear, so top speed is the same. Since the four-speed is already in the truck, I would try that first. Also, if it's a '54 tranny, then it will be fully synchronized, unlike the double-clutcher your truck came with, so that's good. If you then find you don't have enough power to get moving, then maybe your gears are too fast or you could consider switching to the 5 speed to give you smaller steps. Since you're running empty most of the time, the four speed will probably work fine---but it all depends on your gears.
I'm curious about your rear fenders. What did you find to work? The dually rear fenders are very rare--in fact I had to buy a whole 'nother truck to get a pair since mine were missing.
--Bob
Last edited by 46 Dually; 05/10/2008 4:40 AM.
