'06 Yukon Transfer case or transmission problem?

[68lemans462]

I have an '06 Yukon with 137k miles on it. The 4l60e started slipping and it was rebuilt about 4k miles ago. Has worked flawlessly so far. The truck has always had a mild "clunk" when shifting under a light load but the transfer case has otherwise worked fine.

Today while driving I hear a "clunk" similar to the usual clunk but louder and the truck loses power and acts like its in neutral when in any gear. The truck WILL lock the wheels in park. At first the truck didnt want to shift in and out of 4wd, but now it seems to go from 2h/4h/4l ok. No 4x4 errors or codes.. I'm trying to determine if the transfer case has failed or the transmission. What else should I try or test to determine what where the problem lies.. Thanks

 

[rockola1971]

Im a little confused as to your symptoms. Clunk could be your Tcase chain stretched and taking up slack and smacking the inside of the case. Inspect case for damage and loss of fluid.
While in park ALL wheels should be locked in a AWD vehicle. They will NOT turn freely. Tranny in park will NOT turn its output shaft. So input shaft of Tcase will NOT turn which causes output shafts for front and rear to NOT turn, hence all wheels locked.

 

[Bill 1960]

The clunk is probably a loose or broken engine mount trans mount, or front diff mount if AWD. Possibly any bushing loose in the suspension can clunk under sudden torque load.

Doubtful the clunk is related to the loss of drive. Likely the rebuilt trans is the problem.