Have had 98xj for 5 yrs, stock and no drivetrain issues ( auto with 242tc)190k. Highway miles. Within last few months have put Zone 3" lift on (coil front, add a leaf rear). Ended up 3-1/4 front, 4 rear. Wasn't driven much immediately (200 miles?) because youngest was taking it over after 16 birthday. Put tc drop on because of slight vibration. After approx 100 miles after that - he just got legal- noticed a pop underneath at highway speed. I then noticed it again, loud this time. First thought was pin in rear was coming out of carrier hitting housing. Then again realized it felt more as if tc was trying to engage. Pulled onto gravel road, engaged 4wh, and a little pop, fine for a few hundred yards, then almost a grinding noise, comparable to a parking pawl trying to engage when vehicle is still moving. Adjusted tc linkage and seemed to solve issue. Almost, but no. Still have a pop-clunk in tc ( seems like source) and the grinding noise. Nothing is consistent. May drive 20 miles and nothing. Maybe 100 yards and grinding.
So, disconnected tc linkage with it in 2wd and drove. Still have grinding noise, seems mostly around 30-40 mph. Reconnected linkage, no change. Tranny shifts smooth. 4wd works. Under acceleration (hard or easy) in or out of 4wd it pulls and shifts smooth. Cruise speed/ light throttle is problem area with the noise/ grinding. Sounds like a standard with synchronizers gone, except it's an auto, and it's not at a shift or downshift point. I'm baffled! Help, he wants his ride back.

 

How are the engine and trans mounts?

 

they seem fine. Still factory mounts. No noticable movement when going from park to d or r.

 

Have you visually inspected them?

 

yes, when I put drop kit on. No visual cracks, not collapsed, not oil soaked. Just 20 year old parts.