2 ppiece drive shaft question

[kaphillips]

I have a 70 swb 350 th350 truck with 2 piece drive shaft. I am doing a big block conversion and th400 tranny swap. My question is what is the difference between the 2 drivelines. Is it as simple as just adding a th400 yoke on the front shaft or are the carrier bearing, cross member and shafts different on the big block set up. Thanks

[bigmac73]

the 400 tranny has a differnet yoke, I had to get a thick walled yoke and shorten the drive shaft about 2 inches or so , if I rememeber right, this was back in the early 90's,
but i rememebr being told by the garage that did the install to go find a thick walled yoke at a local junk yard, i think cars had a tinner walled yoke

[geezer#99]

Get a new yoke for the T400 and then have a new one piece driveshaft built.

[kaphillips]

If I keep my existing original 2 piece driveshaft factory small block (1/2 ton) set up and change the yoke for a th400 then it would be exactly the same as a factory 2 piece big block would have come ? Correct?

[bigmac73]

no you would have to shorten the front shaft

[Eddie H.]

Another option would be just find a 2 piece driveshaft from a truck that was equipped with a TH 400 from the factory, install new u joints and carrier bearing and you're good to go.

[geezer#99]

Best option is to have a one piece built. New joints, new tube, gauranteed not to be bent, balanced and fit perfect. Usually 250 bucks.
Or shorten yours, new steady bearing, get it balanced and checked for straightness and 3 new joints instead of two. Likely 200 bucks.
For 50 bucks more you're set.

[ItsRandy]

You could use the th350 and use the drive shaft you have as is. Using the 400 is a better idea. If you use the 400 just shorten the front shaft and change the yoke. There is probably a good reason the engineers at GM used a two piece shaft. I have a 502 and 4l85e with a two piece shaft and it works very well.