The 9 1/4 is a C-clip rear. I would never use it
in a car or truck where you plan on bangin gears
or any posi hard launches. Break an axle, and
out it comes. Unless you looking for 3.08 - 3.23
gears, do up a Dana 60 and never worry about your rear again.

If you must do a 9 1/4, then have the different
ends welded on. If you break an axle it stays
in and doesn't wreck your 1/4 panel.
Then you can run a 2.96 gear a fly down the freeway.