The 60-68 MPC
suggests (not going any further than that) that the GT350 4 Speed and C4 use the same
base shaft. It also lumps the FE 4 speed in there. They are talking about just the tube and the fixed ends. The trans yokes are another part as noted in the matrix.
The FE C6 is shown as much different.
After looking carefully at my drive shaft I have to punt as the pits are too deep.
It appears I have to lop off my ends and send in my trans yoke to have a concours shaft made at Deadnutson. They are having supply issues so I'm shafted
for now.