Hello I have a couple questions. Is a driveshaft for a 350 turbo or a 400 turbo the same other then the length? Are the yokes interchangeable?
Thanks Oldsmobile jim

 

Nope, they have different spline counts, with the T400 being larger

 

No to both questions, actually. The yoke is larger on the TH400 and the center-to-center length is different since the TH400 is longer. Also be aware that driveshaft length is also different depending on the rear axle. The pinion flange-to-axle centerline is different on the different axles. And of course wheelbase varies with body style for some years and models.

 

When the PO installed the 455 w/TH400 trans in my 69 they had the driveshaft shortened. As I tried to clear up some vibrations in the car I found that they had not had it rebalanced. It made a difference.

Steve

 

If you're converting from TH350 to TH400 you'll also need to move the trans cross member, change your intermediate e brake cables and hooks as well as install the proper kickdown linkages for the TH400.

 

Apparently the OP is actually changing from a 700R4 to a TH400 (based on a PM to me), so it isn't clear where the crossmember or cables are right now.

 

700-R4 replaced with turbo 400. In regards to cross-member and emergency brake cables. The cross-member fore and aft align to the same holes for the 700-R4 and the 1987 turbo 400 so same brake cable will work... Go figure I don't have that kind of luck! Yahoo.
I stand corrected the 700-R4 is a 1987 the 400 turbo is period correct BOP, and the cross-member does not align to the same holes nor does the brake cable work...