The 70/71 parts catalog and 72 part catalog show the same part number for 1971 and 1972 tachs. Granted, my 70/71 is a final print, so if there was an earlier version, I don't know. I've never had an 8000 tach here, just the 7000. I see some 'restored' 71 cars show an 8000 tach, but as these are available from a wide variety of places, including Classic Instruments, these could have been installed during the restoration.