[200q20v] Drive shaft alignment?

[Reid, Les C.]

Recently had a vibration in the drive shaft and a major oil leak at the
flange seal.
I replaced the final drive seal and bearing and re-lubed the front CV joint
of the drive shaft.

Now for re-installation, the Bentley says to have a special tool to hold the
drive shaft straight.
I did not have said tool and was running out of time so I put it back on
with eyeball method. The vibration sound is gone. But when I have some time
I would like to check the shaft alignment.

Need an easy method to align drive shaft.
String? 2x4? any BTDT?

Thanks
Les Reid