whenever i put my truck into gear (especially reverse) it makes a loud hard knock. my guess is the U-joint but i could be wrong. i had the tranny rebuilt when it was still under warranty. Also my 4WD light is on (no its not in 4WD) anytime i take it out of 4wd the light stays on. not urgent just curious.

 

http://www.dodgeram.org/tech/repair/..._engagment.htm

 

If your u-joints check out okay, then its your rear-end. The crush sleeve preload gets out of whack, causing pinion bearing problems from being loose. IMO, its simply a poor design.

Its common in the 9.25s. Most people just deal with the noise.

Here's an example of what I'm talking about:
http://youtu.be/LEHn8-9exnA