[Jim B]

You seem to imply the car is an acquisition that you don't have first hand knowledge in the build or history. Basically, what has changed since the last known trouble free operation? Such gremlins as actual or transport damage or component swap can enter the picture in a purchased car scenario. (ie, axle housing centered and square in chassis, rear wheels same width and offset, etc.?) A one in a million past encounter was sand/water spilling from a bodyframe cavity after a winter sandblast/caught in a rainstorm caused a pull on the leave although it wasn't as severe as you described.