231 Transfer case, anything to slip in 2wd?

My 97 XJ has a 231 t-case. It has an aftermarket output shaft to eliminate the slip yoke and I put a fresh chain in at the same time 50,000 miles ago. The case has 245K on it. Lately I have been getting what feels like a slip when accelerating heavily in low gear at low speed. It isn't a fast stripping sound but you can sort feel it and easily hear it, I guess it isn't so much a slip as it is a noise and feel. I thought my rear locker might be slipping but I did an assorment of burnouts one tire on dirt one tire on pavement(did it for both sides) as well as a good old smokey pavement burnout lol, no signs that the locker is giving up at all. Its been like 12 years since I was last inside the t-case so I can't picture what is in there to maybe make this noise?

231?... I have a 5 speed and a 231 you can have from a xj

Update, wow I had no idea I dealt with that noise for this long haha the Jeep is not a daily driver.

Found it, the motor mounts and trans mounts had gotten so bad that under power the yoke could move and hit the plastic bracket that holds the wiring for the rear 02 sensor. There was pretty much zero evidence that this ever happened because it didn't do it often and when it did it was just a few revolutions of the yoke before it quit. I still have to replace the passenger side motor mount but a new trans and drivers mount fixed the problem. The passenger side mount is really ok but I figured I should replace it to match the others.

New tires, quiter muffler, new trans and engine mounts and this thing is enjoyable to drive again.