driveshaft help

You Should use them held at both ends and set up rather than the steady rest.

And use a machined joint at each end, take the joint and mill the one side of the cross off..

Slip yokes aren't always perfect, when you true them with a slip yoke they can be off when centered with the joint.

I use a machine that has fixtures for all the different flanges and slips and end yokes we hold them centered exactly how they would be in the car.

They still need balancing, to many differences in weld yoke/slip yoke castings and even tubes.

Use the machined joints in the dead center vs the steady rest