My manual transmission 300E seems to be getting much more "slack" in the drivetrain these days.

I have checked all components individually with the shake and wiggle test. Nothing individually seems to be bad. The flexdisks are tight and the half shafts seem tight, as does the universal joint in the center of the driveshaft. The only thing I can lay this off on, is possibly too much slack in the gear and pinion, and/or the differential unit.

Has anyone experienced this? This is beginning to take away the fun of driving my stick shift car.

Additionally, if I end up rebuilding the rear axle, what gear ratios are available and how much trouble is it to recalibrate the speedometer?

The car currently has a 3.08 and seems too "long legged" for me. This cars M103 engine has a more peaky power band than my C240. I believe the 300E needs the six speed more than the C.

Comments and experiences appreciated,