2004 Laredo (WJ?) 4x4 Auto v6. Thumping noise from rear when over bumps in road. Mechanic said ball joint supporting rear differential. Friend bought a part from dealer using this info. Its a triangular mounting plate with a conical spindle in the middle. Is this the upper axle trailing arm (a-arm) ball joint type mount. Any instructions or advice on locating and replacing it.

 

Welcome to CF.
Yes, that's the ball mount that bolts to the center top of the rear axle housing. It attaches the upper trailing arm to the axle. The trailing arm is shaped like an "A" with the two legs of the "A" attached to the sub-frame forward of the axle, and the point/apex of the "A" attaches to the ball mount on the top of the rear axle housing.
This might be helpful also:>http://www.jeepforum.com/forum/f13/w...emoval-699323/