hi, on my w123, there is a lot of backlash in the drivetrain. i've replaced the differential mounting before, and the problem seemed to go away for a short while, but now its back to square one. what are the points that are prone to wear and can be replaced (without costing an arm)?

if i step on the brakes and release the clutch abruptly in 1st, i can hear the backlash from either the propeller shaft area/differential.

thanks.