after i travel at highway speeds for 30 or more mins. i'll stop at a red light and as soon as i take off from fist to second gears a loud boom that shakes the truck comes from the rear end. it'll continue to do that untill it cools down, and it wont do it untill run it at hwy speeds for a while.

i got a 99 chev tahoe, just bought it. it's in great condition otherwise, 118k

Check trans, transfer case (if applicable), and differential(s). Also make sure there's nothing loose.

is there gear oil in the rear end? the gear oil should be right at the fill hole. sounds like the gears and bearings are getting hot after running highway speeds.

after i travel at highway speeds for 30 or more mins. i'll stop at a red light and as soon as i take off from fist to second gears a loud boom that shakes the truck comes from the rear end. it'll continue to do that untill it cools down, and it wont do it untill run it at hwy speeds for a while.

i got a 99 chev tahoe, just bought it. it's in great condition otherwise, 118k

this i believe is caused by the wrong/contaminated rear diff fluid. replace fluid remove/clean cover and magnet. inspect for metal shavings buy tube of silicone gasket clean sufaces before applying sealant.make sure you use the correct diff fluid use vin to verify..............should take 21/2 quarts............

This is the same sensation I get when the differential lock-up mechanism engages. It should only engage when one rear wheel is spinning faster than the other. This is Chevy's answer to coming up with something cheaper than the posi-trac rear end. You can remove the cover and examine the kick-in device. Good luck.

research trouble code P1870. To get by until I got my trans rebuilt, I would turn the truck off and on again and it would reset until next stop.