Where is the casting number on the crankshaft located? I have a bad vibration in my 460 at idle and at driving speeds that I have not yet pinpointed. The rebuilder said it was a 1971 block and crank, but I would like to be sure. It has no external weights on either harmonic damper spacer or flexplate. The only other possibility I can think of is that the pilot bushing is the wrong one for the torque converter. When I take out the transmission, I sure would like to confirm that my crank is an internal balanced one. Will an internal balance (no weights) flexplate fit on an external balanced crankshaft? Maybe that will be all I need. Thank you for your advice. Great forum!