"clunk" "clunk" when shifting between drive and reverse.

2007 LTZ 173K miles.

I have a loud clunking coming from maybe the rear of the truck under the following conditions:
- When moving and an upshift takes place under LIGHT load. Most 1st to 2nd when going less than 25MPH
- Standing on the break and shifting between drive and reverse

The motor mounts and tranny mount were just replaced and that has not resolved this issue at all. It is very repeatable and sounds metallic.

Vehicle drives rather smooth but does get vibes around 80MPH. Tires are Michelin and have plenty of life left.

Thanks
Bill

Check your u-joints. I've never had on go out on the truck,but it sounds like what I remember on my old camaro

If not u-joints
Check drive shaft slip joint ...

Okay I climbed unerneath and the u-joints appear to be fine. I placed my fingers on the joint and the yokes and felt no slop at all. I feel confident that if I replaced them, it would likey not resolve the issue.

Seems to me the noise is coming from the transfer case. Might this still be the slip yoke?

So what do I need to look for when troubleshooting the SY? maybe rotational slop where it engages the tranny output shaft?

Thanks guys.

I was getting the clunk-clunk when shifting as you describe.

I eventually ended up having the pump-rub kit installed in the transfer case as a preventive measure and that got rid of the clunk-clunk on my 2007 LT3.