I have a 98 with a C8.25 axle and it did leak before I got it and I sealed the gasket. But it occasionally clunks when I brake and when I gas, but its not consistant, only happens on occasion. Also clunks when I shift from R to D and vice versa.

 

I have the same clunk. I have been told its either a U-joint, or the pinion bearing

 

Damn. I know I have a front ujoint that needs replacing already cuz of death wobble but my pinion bearing should be good, there is no residue. Could it be lack of grease? Cuz its not clunking while in motion, just as I initially aply gas and at breaking. Neither are consistant cuz it sometimes won't do it.