reinstalling driveshaft exactly as it came off..
 

what is the crucialness of this? and what is the reasoning behind this?

Shouldnt it not matter how the drive shaft was on there?

Did you just replace both u-joints and possibly flipped it end for end? Or are you talking about marking it in relation to the pinion? For what its worth I've had my driveshaft out probably 15 times in the past year and never once marked it. I just slap it back in, no crazy vibration. Maybe im really lucky....

I allways mark mine and reinstall the same way it came out, may or may not need be, my old uncle taugh me this back in the '50s
just my $0.02' Johnny

yea thats what i mean.. is that what people worry about? vibration?

it can only go on two way right when you replace u joints right?

i didnt mark it last time but for watever reason im reading everywhere to mark it?

Yea vibration is it. After my swap I was using my ls1 driveshaft, swapped it for the lt1 driveshaft cause one of the u-joints were shot on the ls1 and I didn't feel like changing it, no vibration.

You could mark to be safe next time but I never have. With stock mounts I doubt you would feel any vibration. Put polys on there and that may be a different story. If it vibrates just turn it 180.

thanks guys.. absolutely love the forums im learning alot.. hopefully by the time im out of school ill really be able to mod my car ;)