A friend of mine got a 383 built by a local guy who builds engines. The guy said its balanced and such but its an externally balanced rotating assembly and he told my friend that he has to get a weight to bolt to the flexplate to get the balance correct.... how did the engine builder have it balanced if he didn't have the weight in hand? The guy asked me if I knew I had never heard of this before. I told him I would pull the bottom end and send it to someone else to have it balanced correctly with the appropriate externally balanced flexplate. Will any externally balanced sbc flex plate do? Was there a standard size weight for these? Can you get away with using the little weights that bolt on? He said he has the weight but it hits the starter or something so I told him hes probably better off just having it redone somewhere else with the appropriate flex plate. Any input? Im not sure on this one... Thanks!