I've got a couple of tachs here from donors-unknown and the original '6 CYL' and 8 CYL' markings are long ago faded and unreadable. Two have a 5000RPM redline and one has a 4500RPM redline. I *think* all three came from 77AMXs. My guess was that the higher RPM was for the 6, but figured I'd ask others that have such tachs to be certain. Any answers? John