2500HD 4lo Noise

[BEARN]

I was going over a hill today in 4lo. I had it in 4lo to hold back going over the hill. Where the hill was really steep and the truck was holding back it started to pop in the transmission/transfer case are I think. If I applied the brakes the popping would quit but if I released the brake and used engine braking it would pop again. Has anyone had this happen or any suggestions what it might be. Truck info 2003 2500HD gas 6.0 220K miles the transfer case was supposedly replaced around 160K.
Thanks for the help.

 

[Fordum]

When you say popping, was it just a popping sound with nothing physical, or did the truck seem to jerk slightly when it popped?
If it jerked, then my best guess would be a worn chain in the transfer case slipping.

 

[BEARN]

When you say popping, was it just a popping sound with nothing physical, or did the truck seem to jerk slightly when it popped?
If it jerked, then my best guess would be a worn chain in the transfer case slipping.

I think it would jerk slightly. The chain was my first thought but I want to eliminate everything else before I have to pull the case. How would I know for sure it was the chain before I pulled the case?

 

[jekquistk5]

In low there is alot of torque. My dmax made a popping sound while letting off the throttle, or stabbing the brakes. Ended up being the trans mount was ovaled. Something to check.