Thumping once when braking

I recently(yesterday) bought a 93 ZJ, pretty clean besides what one would expect from a 30 year old off-roader. i noticed when driving it home there was a thumping sound when braking. I just tested it again(at 1 am because im the epitome of a healthy lifestyle) and it only happens around 10-0 mph. It only happens once when braking with regular force and is louder with more force on the pedal. It's not a consistent sound like that of a warped drum or rotor either. i tried braking extremely softly in a parking lot and it didnt happen. It sounds like it might be coming from somewhere up front, possibly more towards the driver side but cannot confirm. I jiggled every thing around and it was all tight and not too rusted. I dont really feel anything in the pedal either, just the sound and a very subtle thumping throughout the vehicle. Does anyone have any ideas as to what this could be? Any ideas are welcome, even stupid ones