I got a plan to swap out my rear diff axle and putting in a dually. I ain't doing no conversion. I also plan to extend the frame a long way, to put in a ~ 24' box. Perhaps a frame extension of

Firstly the Dually, can I just put in any dually I see fit, maybe from a chev/GMC, or dodge or does it have to be the correct Spicer on both ends? But if I get a custom driveline cant they fab up whatever I want on each end? This question has no bearing on the next insane thing I got planned, and I need your input on. I know it is easier to just buy what I want, but its expensive and I already got a cheap truck to build off from. Here goes.


Secondly extending truck bed box, do you think this is even sane for a cheap cube "van"/truck. It is a regular cab, automatic 4x4. I really can not see any problems other then a custom drive shaft, extended brake lines/fuel lines, metal frame rail welding, e-brake cable extension. And I have to make sure my transmission can handle the load. Really the load is not that great, maybe 1,000 pounds max. I think I might have alignment problems, but this will rarely do 80kmh/50mph, and frequently do 50km/h/30mph and lower most of the time, stop and go traffic. The wheel base of the rear wheel will be pulled back 16', with a 5' bit hanging past the rear wheel. And 19' from rear cab to rear wheel. I think my main nightmare will be trying to align the rear wheels.

What are your thoughts?




Thanks

 

If you can fabricate, you can put any rear you want on it. If you do "another brand" I'd recommend changing the front spindles too, if you can, so you have the same bolt circle on all four wheels, thus allowing you to carry one spare for all four (six?) wheels.

I've extended, and shortened frames before. Getting everything lined up is time consuming, but very doable. Just don't hack the frame straight down, butt weld the two ends together, and expect it to hold. You need to place C-channel either slightly smaller on the inside, or larger c-channel on the outside, so it fights tightly. Then weld that around the perimeter so the welded area is a bit "boxed".

Aligning the rear wheels (assuming you get the frame the same on both sides) is like any other vehicle - it's a matter of aligning the solid axle so that it points straight. since something this long is unlikely to fit on an alignment machine you align the axle left and right first, so the tires stick out away from the frame the same distance. Once that's done, you can pick the inside edge of the two spring perches, and measure diagonally to a similar point on the opposite, diagonal a-arm. Like an "X". They measurements should be the same. Align the front end first obviously, so the a-arms are in a proper position.

That's how I aligned my old 81 crewcab, with a 24" frame extension between the bed and the cab. if I had the truck still I could take pictures... but alas I don't. I had built a large tool box to go between the bed and the cab, so the bed could be fully used for plywood, sheet rock, and mowers and stuff.

Was a lot of work... might be easier to find an F450 flatbed, stake truck or something along those lines that's already the length you want more or less, then toss your cab/bed on that.