Knock/Vibe in low rpm 6th...Pinion angle?
 

Cruising in 5th at 2k rpms the car sounds fine, if i drop to 6th at about 1400-1600 its ok off the throttle, but if i give it any kind of gas while its kind of lugging, it sounds like something is binding or knocking around under the car. Could this be the angle of the pinion? Im running a 9 inch with a spool(moser) and have a spohn torque arm(adjustable). The part thats confusing me is that under hard accel in the lower gears its fine