Crawled under there and torqued all the bolts on the diff cover before I dropped 300 bucks on a fancy cover.
Glad I did, all of them turned quite a bit to get to 25 foot pounds (I know 30 is the spec, just seems excessive. Pretty sure I only hand tightened them last time I was in there changing the felpro gasket that split and leaked out for the lube locker gasket.
Unfortunately, noticed that opinion seal is also leaking... That's a lot more of a pain in the butt job. So we're just going to pretend we didn't see that for a while.
Now wondering if the Cadillac this axle came out of was in a front end collision or something, maybe pushed the drive shaft into the diff. Because when I checked the backlash when I got it, it was tighter than factory spec should have been and it's supposedly had between 50k and 100k miles IIRC, and now leaky seal after maybe 15k mi.