Adjustable pinion snubbers?

We use an adjustable pinion snubber with Super Stock springs on a '66 Cuda. 417 small block, 904 auto, 4:10., 9by28" slicks. 1.47 sec. at 60'; best time is 10.86 @ 124. This car is 100% street legal. What also works is CalTracs with M/T Radials