The E36's rear half-shafts carry CV joints at each end — not a routine wear item, but they do fail, especially under track use and higher power, where a worn CV can click, clunk on throttle transitions, or vibrate under load.
The first sign is usually a split CV boot flinging grease — caught early, a re-boot and re-grease saves the joint, but a boot open too long lets grit in and ruins the CV
…