alright i put a 4.3 second gen with a 700r4 with matching chevy transfer case

was out on the trail last weekend and my transfer case is knocking but only happens in 4 low under a high load ????

dosen't happen in 4 high or two wheel any suggestions?????

 

i believer it would be a np203 or np205 if im correct, which is a chain driven case, it could be the chain strecthing slacking, suggestion, new case, there a dime a dozen

 

A NP 205 is gear driven But if you have a 203,208, 231 .... you could have a stretched chain when you get it in a bind it is jumping teeth if so don't replace it unless you have a cheep one or even better free a chain is just $40-$60 depending on your parts connection to diagnose it put it in 4 wheel low in a paved parking lot drive it in a circle if it has a consistent pop as the vehicle jerks sideways this is probably what it is