I  have a 1987 Jeep with the straight 6 cylinder 4WD.Question:  I hear a clunk from the rear end when I put it into gear to take off, can you help me?Answer: Pinion Yoke Spline Excessive WearChirp or clunk sound when you place a car or truck into reverse, or sometimes whenever shifting from park to drive or low gear.This problem is typically caused by wear or abuse and requires that you install a new pinion yoke.  You can test this before removing the driveshaft.  See if you can move the driveshaft up and down just before where it enters the differential.Pinion Yokes can also be damaged by worn out pinion seal, see photo (willberry).  You can see the new yokes we provide on our site.