Drive line clunk

I have a 05' Sierra 1500 ext cab 4x4. My problem is when the truck downshiftes from second to first there is a loud clunk from the rear end it also does it when it upshiftes n the same gears. I have had it back to the dealer four times and they keep saying they can't hear it or that t is normal, there is no way this sund is normal! If anyone could offer me some help I would be very greatful

Assuming the truck is still under factory warranty, and you have not already done so! Try taking your truck to another dealer if at all possible. I had a irratating problem recently with my truck (not at all related to your problem), a 2004 2500HD.

I took it to one dealer 3 times they did not fix the problem and told me nothing else could be done. I then took it to another dealer with the work order from the first dealer. A more experience tech looked at it and determined they did not go far enough in their dianostics.

The part was ordered, replaced and the problem solved!!!

Moral of the story, is it may just be that simple!

Good luck,

GM calls it normal, no repair needed. Usually hear a clunk or clank between 2 to 3 shifts and 3 to 2. It has something to do with the #2 clutches not releasing all the way. Also check your slip yoke going into trans. It most likely is loose. They have a nickel plated one they replace it with. Check the silverado forum and you will see other horror stories.

Assuming that this is an Automatic transmission, check the ECM diagnostic codes. There is a notorious problem called DTC code P1870 that causes the torque converter to lock at low speeds, causing a very harsh shift, particularly the 1-2 shift.

I usually get the problem 2 to 3 shift. I dumped a bottle of lucas trans additive in and put on about 400 miles. I have noticed it once since then. I'll check the codes this weekend. What I understand it's the #2 clutch not releasing quick enough. It's an '03 5.3 Z71 4x4 auto w/3.73 rear.