Try replacing the u-joints & see that makes the clunk go away. It doesn't take much play to make a lot noise.Not sure about the rear axle, seems like there shouldn't be much play there either. John WC Roddick wrote: > Our '64 has an 8.75" sure grip differential. I have the > car on jack stands and the drive shaft removed. When I > rotate the rear wheels I get almost instant movement of > the pinion flange, but when I rotate the pinion flange > there is much more "slack" before the wheels begin to > turn. It seems to me that the amount of "slack" should be > the same regardless of which "end" I am rotating. Is > this behavior normal for the sure grip rear-end, or do we > have a problem? I am trying to find the source of a > "clunk" in the driveline, when I shift out of neutral into > reverse or a forward gear. The "clunk" is kinda loud, and > has a sort of bell ring sound to it. The front U-joint is > a bit lose, but side-to-side not rotational, as though the > ends of the "cross" were worn. I will replace it anyway. > Also sent the center support bearing insulator to the > Damper Doctor for rebuild. The rubber was intact, but > sagging due the car sitting idle for 12 years. Any > advice? Thanks.Bill & Tami'64 Crown