['ol Pinion head]

Originally Posted by unruhjonny

ok - thank you VERY much HFR!!

Is it correct to assume that the 49.2" vs 48" is a center to center of u-joint measurement?

And one has to have the correct T-400 yoke otherwise will be too short w the 48" driveshaft.

Notice the 1.2" difference in lengths between T-350 & T-400 for '70 models?

The '70 F-body T-400 driveshaft takes the long Spicer 1310 T-400 yoke.
The machined surface, aka, the shaft, portion of the yoke is near 6 1/2" long. That's the longest version of over a dozen different styles of GM usage T-400 yokes.

For '71 model Birds, Pontiac went to a longer driveshaft for T-400 & M20/M22 usage. That little over 48 1/2" long driveshaft utilizes 3R u-joint, as does its mating ("med length") T-400 style yoke.

'72 models Birds factory equipped w T-400's & Muncie 4speeds reverted back to the small Spicer 1310 u joint & that style was used through the '74 models.

Have pulled several clean original F-body T-400 driveshafts over the years, still have at least one '70 version. Back in the early '80's, had a '75 up V8 T-350 Bird driveshaft cut down 5/8" for my '80 when I briefly swapped out its Turbo 301/T-350 for a '70 YZ 400 & PQ T-400.