after a 4000rpm launch last night the car made a big bang noise followed by "thwacka thwacka thwack thwack thwack " rythmical banging that woudl come in and out...

Facts so far:
- car handles fine
- car drives straight
- power seems ok
- axles are not broken
- sometimes amongst the whacking it sounds like one of hte tyres at the back has locked up and is skidding just a little bit.
- noise appears on power on more, power off (neutral) sometimes.

Noise appears to come from the center of the car right near the middle of the underside of the car. (dead center from the front to the back and side to side)

Could I have damaged the driveshaft? or maybe the diff? wouild the car move if the diff was stuffeD?

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