Ok i have a 91 nissan 240sx coupe and i was driving to check some property out and hit a huge bump i was wondering if there are like weights that balance it out or what caz when im starting off it clunks really bad but other then starting off its perfectly fine so i jacked up the car and down low the shaft wobbles and after the lil start it gets straight dunno any input would be great

 

Does it have 'normal' U-joints? One's bad. There might be balance weights, but your description really sounds like a bad U-joint. Find which one's loose & replace it.