drivetrain shudder? driveshaft length?

well all the mounts are new, u joints are new, rear springs are new. just restored it!

Drive shaft, stock/original ?
Seemed you had some question about it. What do you have ?

If it is the same shaft,one trick is to unbolt it at the rear u-joint and spin it 180 degs,and bolt it back in. Thus putting it back in exactly as it came out.

My next question would be about Harmonic balancer and flex plate.