Low speed grumbling - not cornering
 

Around 25mph, I get a loud growl from my drivetrain somewhere. I mostly notice it on decel, but I'm not cornering or reversing. It happens when driving through a 25mph zone or when braking. It seems to be independent of clutch or RPM (I get it when doing 25 in 2nd at 2K or in 1st at 3500). Since it's not cornering, I don't know if it's the LSD or something else. I can't recall if it's always done this or not. If it's just starting, it's been gradual. The car has 100k on it. I bought it at 95k. Clutch was replaced at 65k. The rest of the drivetrain is original.
Thanks for any ideas.

Wheel bearing perhaps ?

It seems to be from both wheels equally. I've been doing a lot of research on the bearing replacement and it sounds like something I don't want to do for the fun of it. I think I'll jack it up and make sure it's not tire noise.

High mileage CV joints will do a low pitched growl upon decel early on then get worse over time. Check CV bolts on both ends to make sure it's not just loose bolts.

Front wheel bearings and CV joint are both easy DIY projects.

Yeah, but rear wheel bearings aren't. Not that I won't if it needs it.
CVs probably need a good inspection anyway. It's been at least 35k since they were done, if they were even done then.

I guess I forgot to mention that the rumbling seems to be coming from the rear.