cummins swap?

[chivo]

Im going to swap the big block in my 87 1ton srw for a cummins and have tranny questions. i want to keep my round np 205 case. I have a nv4500 from a dodge 5.9 gasser 4x4 with a round 241 tail housing that is the same pattern as my 205 what route should i take?
1 cummins input shaft, bearing retainer, and a gm main shaft?

2 find a gm nv4500 and put a cummins input shaft?

3 build a cummins nv4500 and try to find an adapter from 29 spline to 32 spline if there is one i cant find it?

4 if theres another route im missing please school me!!!!

 

[Stomis]

The other route is to go full GM behind the cummins using a bread van adapter. This will allow you to retain your drivetrain exactly how it is and will be the easiest solution.

The only downfall Im aware of is that the adapter deliberately has some sort of angle built into it, marginal I believe like 10*. Guys still use them allt he time and it causes no issue from what Ive read.

 

[chivo]

That is something I have thought of since im not going to hot rod it and have a good 400 in the truck now. I have already bought a gen2 adapter plate flywheel starter and bell housing so im kinda committed to a standard. Plus I really prefer manual over auto.

 

[Stomis]

That is something I have thought of since im not going to hot rod it and have a good 400 in the truck now. I have already bought a gen2 adapter plate flywheel starter and bell housing so im kinda committed to a standard. Plus I really prefer manual over auto.

Believe me no one advocates a standard trans over an auto more than me. I wasnt suggesting you run the 400 but simply use the 400 adapter to get a GM nv4500 behind it, then you can just bolt your 205 straight to that.

If you're stuck with the dodge bell and adapter than Im afraid Im not help. I dont have any experience with swapping inputs and outputs to cross brand platforms. I will say that I would gather that swapping the input shaft on the tcase is probably the simplest method.

 

[chivo]

See now theres something that slipped my mind. I have to build the tranny regardless of what I do because its a gasser. So I could just build it straight up cummins with upgraded 5th gear . Being the gm main shaft doesnt have an upgraded 5th. Then just swap my 32 input to 29. Thats sound like a plan. See you were a help !

 

[chivo]

Or not looks like the 29 spline inputs are male. This would cost too much seeing how i can build it with a gm main for around 500$. quad4x4s kit is 450 then i need to put some sort of adapter in between the tcase a trans because of the length of the conversion puting that option around 6 or 700. plus the cost to build the trans.

 

[kennyw]

From what I understand, the GM main shaft doesn't need to be upgraded because the balancer prevents 5th gear from falling off.

 

[rompinstompinmudmonkey]

Swapping the input on the 4500 is easy. if I was doing it I would find a gm 4500 so it mated to the case. Swap the input to the larger 1 3/8" shaft and make sure you address the 5th gear nut. I'm not sure what the difference is between the gm 5th gear and the Dodge 5th gear. I would assume that it's possible to modify the 5th gear nut and put 3 set screws in it similar to how some of the Dodge locking nuts are

 

[chivo]

Swapping the input on the 4500 is easy. if I was doing it I would find a gm 4500 so it mated to the case. Swap the input to the larger 1 3/8" shaft and make sure you address the 5th gear nut. I'm not sure what the difference is between the gm 5th gear and the Dodge 5th gear. I would assume that it's possible to modify the 5th gear nut and put 3 set screws in it similar to how some of the Dodge locking nuts are

I will definitely address 5th gear on the gm shaft. My dumb ass already bought the trans so now I have to make it work. Looks like gm main and cummins input it is. This would be the cheapest route it seems.

 

[Hogback Fabrication]

I don't think there is a 5th gear "fix" for the GM shaft, I believe they are setup differently.

 

[chivo]

I don't think there is a 5th gear "fix" for the GM shaft, I believe they are setup differently.

Your right but I plan on drilling and tapping the nut for a set screw. That will be a little added insurance if I dont put the balancer on it.