When running a 9", does the driveshaft need to be shortened? I know this is the case with a 12-bolt.

I'm hoping a driveshaft 3/4" shorter than stock will work with a 9"

 

I've done two 9" installs in my f-bodies, and the stocker was the correct length both times. There are two different pinion yokes for the 9" diff, though - a short and a long one. The short yoke fits perfect for the stock length driveshaft. Maybe try the long yoke? Not sure the length difference between the two, but I think it's around 1" longer.... that would get you close. Call Moser up - they'll definitely have the answers.