Ok so after a week of being under the weather, I finally got under the car today. Checked all the mounts, driveshaft, axles etc and didn't see anything that looked suspicious. So I took and drained the diff fluid and nothing jumped out to me other than how black the fluid already is. And the amount of goop on the drain plug was alarming until I saw some older threads with pictures showing the same thing. So at this point I can't find what made the noise and everything I checked was tight and right so I'm moving on at this time.
It seems the majority here stick with gm differential fluids? My question is in the owners manual I see 88900401 and it calls for ls additive 88900330. But I've seen others using 88862624 which already has the additive added but shows it's for the zl1.
Can somebody help me on which of these 2 to buy tommorow? My gut says 88862624 would work but not sure.
Thanks guys!
