Is the driveshaft out of a 68-72 grand prix with a th400 the right length for a 68-72 Skylark short shaft TH400? I have read that the Grand Prix is the same as a A-body from the engine back.
You have to watch which rear it had. If it's an 8.2, the length will be slightly off from an 8.5 rearend. Also watch the rearend's yolk as the 8.2 used u-bolts while newer stuff used the steel straps.
'69-72 Turbo 400 GrandPrix driveshaft is same length as '68-72 Pontiac GTO Turbo 400 driveshaft, 55.375" u-joint center to u-joint center. As from the factory, this era Pontiac GP, GTO, & LeMans came with either a 8.2 Pontiac rearend, or a 12 bolt, if such a car now has a corporate 8.5 10 bolt r/e, then driveshaft will have been shortened at one time, 7/8" to 1 1/8". Do not have factory '68-70 GS driveshaft length spec at hand, but from having several driveshafts made for this application in the past, believe they are slightly shorter than the same era GP & GTO offerings. FWIW, my #1 driveshaft donors to cutdown usually come from our 2 door '68-71 Pontiac Tempests & LeMans partscars. This era Pontiac A-body with either a SuperTurbine 300 (2spd) or Turbo 350 trans, will have a 56" center to center length driveshaft. Many '72 A-body Turbo 350 driveshafts are "rubber isolated" two piece tube affairs & we always chunk those. :3gears: Roger