i found an Open Differential for sale(Differential with Ring Gear and Pinion already installed.. will there be any need for alignment like shims and stuff? if the pinion and ring gear are already installed?

 

Question kind of unclear. If you are saying you found a complete rear end with a gear you like, but an open carrier, and can you just swap a posi carrier for the open one?... the answer is... maybe. You won't have to mess with the pinion depth, but you might have to mess with the carrier shims. These position carrier from side to side, backlash. This isn't that bad; if you have too little backlash, you put a thicker shim on the passenger side, and put a thinner one on the drivers side, and vice versa. Don't have to do a lot of disassembly for this, just need a dial indicator w/magnetic base.

Also, there are different series carriers, 2 series & 3 series for the 7.5 diff. There are 4.10 gears that will fit a 2 series, 4.10 gears that will fit a 3 series. So if that open carrier is a 2 series, and it has a 4.10 2 series bolted on it, that 4.10 gear won't work with a posi 3 series carrier.

This is from richmondgear.com:

ratio teeth Part No carrier
2.73 41-15 49-0048-1 2
3.08 40-13 49-0001-1 2
3.23 42-13 49-0044-1 3
3.23 42-13 49-0003-1 2
3.42 41-12 49-0045-1 3
3.42 41-12 49-0005-1 2
3.73 41-11 49-0046-1 3
3.73 41-11 49-0007-1 2
4.10 41-10 69-0322-1 3
4.10 41-10 49-0009-1 2
4.56 41-9 69-0324-1 3*
4.56 41-9 69-0326-1 2*

* Special Cross Pin 80-0270-1
required.
2 Fits 3.08 and numerically lower
carrier.
3 Fits 3.23 and numerically higher
carrier.


If you are saying you found just the carrier with the ring you want bolted to it....and you want to unbolt ring from it, pop it on your posi carrier and put it in your rear end with it's matching pinion.... install from scratch needed. If it's the right series. clear as mud