Rick, I was only partially correct. Real_fast, the face is definitely from a 6K tach - that's for certain. I didn't notice the discrepancy in your part number beyond the last digit. The number stamped on the backside does not correspond to any of the 4 listed numbers as was indicated previously. The number on the backside of this tach is 6412295. There's one digit off in one of the last two positions - take your pick. Given that the face has been altered, I suspect that the stamp may also have been faked but with an error. The other possibility is a stamping error at the factory, as Rick suggested. In either case, this tach did not start out as a 7K unit.
