99 Tahoe rumble

I have a 99 Tahoe 2 door with 141K on it and I am having a slight rumble once I get above 40 mph. I changed the plugs, wires, and distributor cap. I also just replaced the rear driveshaft U joints expecting that to be the problem since it has before but I still have it. The tires I have are Wrangler Armortrac 265 75R16. Any ideas? Thanks.

I have a 99 Tahoe 2 door with 141K on it and I am having a slight rumble once I get above 40 mph. I changed the plugs, wires, and distributor cap. I also just replaced the rear driveshaft U joints expecting that to be the problem since it has before but I still have it. The tires I have are Wrangler Armortrac 265 75R16. Any ideas? Thanks.

did you ever remove access cover , and inspect,clean, and replace the rear diff / fluid ?????

Nope its looking like that is the next route to go. Thanks.

Nope its looking like that is the next route to go. Thanks.

the rear diff requires the inspection cover to be removed..the fluid usually needs replacing every 30-45,ooomi...the gears,box,magnet needs cleaning,,,,lots of metal dust in there...

when the quick lube shops do this they do not clean anything..they suck out /drain out old fluid install new into the debris ladden differential ...

use mineral spirits and a cloth to wipe off the goo...