Into the tranny it doesnt really matter.
If you can find the old "mark" (ghost rust pattern) on the pinion, then try to install it that way.
p.s. Be careful with driveshaft bolts and the threadlock!!! You gotta have a lot and make sure they are in good condition. At $1/bolt new, get some new ones, or at least keep an eye on them after you put them in!
