if it is popping/jerking from reverse to another gear, it is loose driveshaft bolts, mine did it for a while and i tightened the bolts from reading somewhere else in the past, fixed the problem and then a week or two later it did it again, so i just let it go. if you want to go w/ a trans additive to check just incase id personally try the lucas tranny slip additive, it does more than just fix spools in the tranny that cause slipping. if it is jerking thru all gears when driving it may be the tranny or the torque convertor. ive heard of using marvel mystery oil as well, but have never done so, so i cant tell you anything on that one.
