changine gears in a 9" ford

[chevy 37]

I'm going to change my high gears for some 3:55 but also want to change to Posi. Whats involved in the posi change over. Do I need to get a new pumpkin?

[cffisher]

If I were you I'd get a spare pumpkin. The rear you have would be a good spare and the new gears and posie will probably need different shims. Depending on what your changing to the ring gear will be a different thickness. 9" pumpkins aren't that expensive.