Dually swap with 14 bolt axle

Idahoan6-0 · September 1, 2020

Recently I picked up an older '92 k3500, and did a transmission swap. Sadly the transmission I got had already started going out, and with the old motor it's not worth putting more money into it for me. That being said, I'm thinking of swapping the rear end into my 02 3/4 ton. I've heard the axles are different widths, is this true? If so, could I swap the leafs and all from a long bed dually to a short bed?

And one more thing- I'm driving down to California shortly to pick up a camper. Well within my 3/4's rear axle capacity. Could I swap the front wheel spacers on my dually to the current rear axle and stick the duals on? With a 16 hour total drive ahead, I'd much rather have the duals for stability in the back and protection from blowouts. Is this something that'd be safe? I'm running short on time with a sliding fiver hitch still needing to get installed, so swapping leafs and the axle before the trip would take too much time.

Thanks for any input

davester · September 1, 2020

First, the axles are from different generation trucks, so nothing would line up, even if it were the same "size" truck.

The DRW axle is significantly wider than the SRW axle (for the same generation truck), about 6-8" or so, so the inner wheel is only a little bit closer to the frame (with the offset rim).

If you just modify the frame/axle so you can mount it up, your SRW wheels will be sticking out a fair amount.

If you want to run dually wheels, I don't know about the relative axle/frame widths between the GMT800's and the '92 truck. But even if there was enough space, you likely have to cut off the spring and shock mounts from the axle and reposition them for the '92 frame. And you'll need to jam on dually fenders as well to be legal. Probably also will have to do something to the driveshaft (perhaps change it's length a bit, or have a different yoke thingamabob at the end.

Since you said you were short on time, I would say this isn't the thing to do...

davester · September 1, 2020

And, as a further note, if the drw is a cab&chassis, then the axle is narrower than both the srw & drw (with truck bed) axles.

And the older drw axle might not take the power that the '02 powertrain delivers, particularly if it's got the duramax.

And don't forget that it needs to be the same ratio as the front axle if the '02 is a 4x4 and you want to use 4wd at all.

Edited September 1, 2020 by davester

Idahoan6-0 · September 2, 2020

20 hours ago, davester said:

And, as a further note, if the drw is a cab&chassis, then the axle is narrower than both the srw & drw (with truck bed) axles.

And the older drw axle might not take the power that the '02 powertrain delivers, particularly if it's got the duramax.

And don't forget that it needs to be the same ratio as the front axle if the '02 is a 4x4 and you want to use 4wd at all.

Thanks for the info, I am looking to run duals. I'm gonna check the body builder manuals for the frame differences, but from what I've seen they seem pretty close. I'm also running with a 6.0 vortec, so power shouldn't be an issue. I can't imagine that axle not being able to handle that, even with the gearing being so high. After some further research it looks like all the dimensions for the actual mounting are just about the same, except the leaf mounting points are about an inch different per side. Is that tolerable or do I need those mounts moved over (or the leafs spaced out from the frame?)?

Also looks like I can relocate the spring perches if everything else works together, and it looks fairly easy just takes a bit of time.

Edited September 2, 2020 by Idahoan6-0