If I buy a r200 powerbrute lsd for 12mm gear bolts, what would I need to do to put it on my z? I currently have a r200 with 10mm gear bolts, if i need to change diffs what diff do i need and what axles do i need?

Check out this post:

http://www.classiczcars.com/forums/showthread.php?t=15798&highlight=R200+LSD

I think his question was in regards to how you get the 12mm carrier to work with the 10mm bolts. Not a problem. The bolts go through a hole in the carrier and then screw into the threaded holes in the ring gear. All you need to do is get some ring gear bolt spacers to take up the 1 mm gap between the 12mm hole and the 10mm bolt. They don't have to be exact or super tight, they're just taking up the space so that the ring gear gets bolted on straight.

Here's what you do:

Look up stainless steel tube on the internet. You're looking for something with 12mm OD and 10mm ID. You'll probably have to buy a stick of tube that might be 4' or 8' long. Get the tube, and cut the pieces to the right length to fit the carrier. Deburr the ends, and stick them in the holes. Then just bolt it all together. Easy to do, and you can recoop your cost on the tube pretty easily. Just make more sets of spacers and sell them on here or hybridz or zcar.com. I bought my spacers to install my 12mm carrier on my 4.11 with 10mm bolts from someone who had done just that. I would just give you his email but I know he ran out already. He did tell me that he did more than break even on the spacers and he was charging $20 per set.

Your side stub axles should plug right into the LSD. Mine from an 80ZX plugged right into my 87 300ZX carrier.