Well the mechanic im taking mine has done several rebuilds to Z and Subaru rears. There is lots of subaru parts here, but that 800 bucks is just too much. I just dont see the sense to replace it with another noisy rear either. But im still looking to complete that parts list..

Hey, just came across this rebuild kit on zcarsource -

http://www.zcarsource.com/differential-rebuild-kit-r-180-new_8_52720_65984.html

Also, some individual parts listed -

http://www.zcarsource.com/r-180-differential-parts_8_52720.html

Whoa. 400 bucks?

I must have ESP...

Yes, everything on that site is kind of expensive. But at least you have the list of parts that are typically replaced. Take that list and use this site to get part numbers - http://www.carpartsmanual.com/datsunS30/DatsunZIndex/PowerTrain/DifferentialGear/R180/tabid/1726/Default.aspx

Then go to this site and put the number in the search box to see if it's available and get a price (I put a sample up of the pinion bearing) - http://www.courtesyparts.com/bearing-ba-p-351811.html You can order from the site or by phone, they're very professional and will get you the parts if available.

Or, you could get the bearing part numbers directly off of the bearings and cross-reference them or buy them directly from a bearing supply house, like the one jmortensen suggested. The Courtesy Nissan bearing prices aren't terribly high though and you'll get factory spec. bearings.

Here's the other pinion bearing, you can see why the kit from zcarsource is so expensive - http://www.courtesyparts.com/bearing-pi-p-350552.html

Have you checked cheapest shipping available for a 70? lb chunk of iron? I got $238 using these guys - https://www.ipsparcel.com/rate.cfm