72 340 engine in 67 barracuda around 60 mph have a small vibration you feel in the seat not the steering wheel. New 904 Tci Streetmaster trans new 8 3/4 355 Posi rear. New drive shaft also. Wondering what it could be?
Pump seems to work ok it is either the shaft seal or the reservoir O ring. I think it is running down behind the pulley and dripping on the lower radiator hose.