Urgent help! Th350 to th400

[INSIDIOUS '86]

So we are swapping a th350 and 305 combo out for a 454 an th400. PROBLEM! Th400 had a bolt on yoke. It's from a suburban and the truck is a 81 shorty. What can we do about the driveshaft? It has to be cheap and quick though if possible
Posted via Mobile Device

[KQQL IT]

Slip on goes on a bolt on style.
Posted via Mobile Device

[INSIDIOUS '86]

So what do we need? I know it needs slip in the driveshaft. The th350 is a long shaft trans and the th400 Is shorter.
Posted via Mobile Device

[xrcr]

Look at this and see if it helps http://www.maliburacing.com/auto_tranny_id.htm
You need to get a slip in yoke and have at least 1" in the tailshaft maybe 3/4 but I don't know. I put a 350 in a 4 speed truck using a driveshaft that was behind a 700r. had to change to a 9" tail on the 350

[old Rusty C10]

I have always had long bed pickups . The driveshaft with a th400 was always a slip in like on the th350, however the shaft on a 400 was always a two piece. UNfortunately when you are customizing things, its never cheap or easy. IIRC the tailshaft on the th400 is either long or short tail much like the th 350. the short tail is the one with the bolt on driveshaft. the vast majority of the short tail ones were in vans and those van cab truck body trucks they make. Im thinking your only way out is to have a driveshaft custom made.. Also every th400 ive seen in the pickup has a carrier bearing that needs to be installed on the frame..

[KQQL IT]

You will need a th400 slip yoke and a drive shaft shop to shorten the drive shaft and attach the new yoke.
Posted via Mobile Device

[KQQL IT]

http://www.drivelinesnw.com/
Posted via Mobile Device

[INSIDIOUS '86]

Alright so I can either convert the trans to slip yoke or have a new driveshaft made basicly.

Can't gO two piece cause that will be too weak for a truck like this that will see track time
Posted via Mobile Device

[INSIDIOUS '86]

Originally Posted by KQQL IT

You will need a th400 slip yoke and a drive shaft shop to shorten the drive shaft and attach the new yoke.
Posted via Mobile Device

Also are you saying that a bolt yoke trans will take a slip yoke if we got a longer slip yoke to go in?
Posted via Mobile Device

[KQQL IT]

Track time? Well the U joints will need to be 1330s if not 1350s. Which means a brand new shaft...
id guess a 305 t350 would be 1310 ujoints.
Posted via Mobile Device

[Desert1957]

http://ls1tech.com/forums/automatic-...questions.html

http://www.chevelles.com/forums/show...put+shaft+yoke

This is the best web site I can give you, It list ALL the available yokes for 400 Turbos.

http://www.dennysdriveshaft.com/c8_t...lip_yokes.html

Desert

[Desert1957]

I think this is the one you need to replace a bolt on yoke, with the short output shaft splines on the tailshaft.
http://www.dennysdriveshaft.com/p108...ine_th400.html

Desert

[INSIDIOUS '86]

Going to have my buddies at Drivelines nw build a driveshaft that will adapt to the trans. Eventually this th400 will be built for a 600hp bbc and have a gear vendor on it or he may go the 700r4 route. Either way we just need to get it moving though.
Posted via Mobile Device