That will allow you access to the front differential bolt.  You should have enough room to slip a new cushion in without having to drop the whole differential out.

 

'80-'82 aluminum rearends are much easier to R+R than the '63-'79 era. The upper mounts on the '63-'79's are way different than the '80-82's.

I have R+R'ed mine in under 4 hours without any hassles.

 

Good luck!