1988 R20 2WD TH 400 to 4WD

[Knuck55]

Greetings, Has anyone converted a 2wd 400 to a 4wd unit? I have the correct 208 mount for it and have measured and I have heard you can cut some of the shaft to make it work without tearing into the trans. This only has 34,000 mile on it and I really dont want to tear it down for another shaft. Other than that the conversion has been going good. Have a friend that owns a driveshaft shop so good there. This was an incredible survivor find I got 2 years ago. 454, Corp. 14 with a 10.5 ring gear. Bombproof! Guy special ordered it to just pull a giant trailer.
Thanks for any suggestions

 

[PrairieDrifter]

I'd imagine it has to be a short tail shaft like the 2wd th350 swap. As long as there's enough splines to cut some off. I would also try to keep the heat out of the shaft while cutting it in my opinion. Otherwise the output shaft will need to be swapped.

 

[nvrenuf]

I’ve done it with a couple of 2wd 400’s but I used them on a figure 8 pattern 205. The transmissions I used were a short tailshaft version with a short tail cone, once removed the tailshaft stuck out 4.5”. These transmissions were a direct bolt up to a figure 8 205 with a factory adapter. No mods.

All that said, *I think* a 400/208 combo uses a tailshaft that sticks out 2.5” which I don’t believe is used in any 2wd application. I don’t know if there’s enough spline on a 2wd trails to cut it down.

 

[Ricko1966]

Greetings, Has anyone converted a 2wd 400 to a 4wd unit? I have the correct 208 mount for it and have measured and I have heard you can cut some of the shaft to make it work without tearing into the trans. This only has 34,000 mile on it and I really dont want to tear it down for another shaft. Other than that the conversion has been going good. Have a friend that owns a driveshaft shop so good there. This was an incredible survivor find I got 2 years ago. 454, Corp. 14 with a 10.5 ring gear. Bombproof! Guy special ordered it to just pull a giant trailer.
Thanks for any suggestions

@NickTransmissions wrote about this yesterday for another member and why cutting the shaft wasn't a good idea. Now that I've tagged him on it maybe he'll chime in here.

 

[Knuck55]

Great, Thanks Ricko. Not to experienced on this forum stuff. Will try to search for it.

 

[bucket]

A member here did such a swap several years ago. He simply had a block of aluminum machined as a spacer, to make the 2wd output shaft length work. I'd tag him, but he hasn't been around in years.

 

[Ricko1966]

Great, Thanks Ricko. Not to experienced on this forum stuff. Will try to search for it.

I found it,he just said it wasn't a good idea,no explanation since we tagged him I'm sure he'll chime in and explain it for us.

 

[NickTransmissions]

To whom it may concern - just swap the output shaft..Takes literally 10 minutes to evacuate the case, swap the shaft then another 10-15 minutes for reassembly. not rocket science and certainly not worth hacking the output shaft, potentially ruining it...Yes, I know there are people on Youtube doing these conversions on various transmissions by taking a hacksaw to the output shaft and I suppose it's your property - do with it what you will, but it would be a very cold, freezing day in hell before I would ever do that to one of my transmissions.

 

[Matt69olds]

To whom it may concern - just swap the output shaft..Takes literally 10 minutes to evacuate the case, swap the shaft then another 10-15 minutes for reassembly. not rocket science and certainly not worth hacking the output shaft, potentially ruining it...Yes, I know there are people on Youtube doing these conversions on various transmissions by taking a hacksaw to the output shaft and I suppose it's your property - do with it what you will, but it would be a very cold, freezing day in hell before I would ever do that to one of my transmissions.

I’d agree, it will take longer to clean everything than to swap the shafts.

Watch some YouTube videos, work slowly and cleanly, don’t force anything. feel free to ask questions.