I shift at 6,200 rpm. Rev limiter is set at 6,600 and I've bounced off it a couple of times. Chrysler claimed in their engine book that they are good for 7,000 rpm. I am not sure I would try this on a circle track or road race engine due to all the thrust reverseals. My crank is an original '79 CFD casting that is internally balanced and polished, but never turned, still standard size. It's also been in two different blocks and must have at least 300,000 miles on it by now. Chrysler had two different sources for 360 cranks. Both are cast, and most were cast in a Chrysler foundry. Some however were cast by GM for Chrysler and are identified by the letters CFD. Or at least that's what I've been told.