Transmission or rear end?
Took the 49 out for a test drive after making a few changes to the engine. The car ran well except for when I either accelerated rapidly or let off the gas quickly, at which point it the car would lurch and make a loud bumping sound. I can't tell if the "bump" sound is coming from the rear end or the transmission. I wonder if the driveshaft is engaging the rear end too hard or if the clutch is slipping. When decelerating quickly, when the hard thump sound occurred, the car would sway slightly. Any ideas?