Work has been a bear lately, haven't had much time to work on my own car much less Matt's car. But today is not a work day!
2.93 out of Matt's car. Lame.
3.15 out of a junkyard 325i... cool.
Fluid looks fine, as it should.
Once you remove the axle seals, these snap rings are the next thing you face in disassembling one of these things.
These snap ring pliers are the only way to get these snap rings out. On an E46 the snap rings double as retainers for the outer bearing races and as the axial locators of the differential unit. They're marked for their thickness (in mm, between around 3.4mm and 4.0mm). Generally, when installing an LSD you can get away with retaining the stock snap rings which is why I write their sizes on the case, but there are still a bunch of measurements that need to be taken to make sure. BMW doesn't sell these, so I keep a collection of about 30 of them to be able to build differentials without resorting to other methods.
The gears inside this diff looked great, and there is no noticeable bearing wear.
Next I got to pulling the driveshaft so I could do the giubo and pull the transmission to do a clutch. This is not the worst giubo I've seen, but it's bad. Very dry rotted.
Looks like it needs a transmission tailshaft seal. Usually things are not this oily.
