I thought you and The Beach Boys were on to another song! My 2 ton with the SM420 will run smooth under load, bearing noise in the tranny when decelerating, push the clutch in while coasting at speed and it still has some noise.

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy