Motive gears and spicer SG. Dr Diff said Motive was a good gear set. I will get the mechanic to check it out and see if everything is in specs. I also have a Duster with 400 HP on the dyno and an 8 1/4 with 3.91 and SG with a set of MT street radials. No problems!!!!! Will try for 450 HP on a stroker for the Dart but will likely switch to an 8 3/4, but that is down the road.