This hood tach came with the stash of parts I received when I purchased my 67 GTO. The car was not equipt with a hood tach but I know at one point the guy also owned a 71 GTO. I am trying to figure out what the actual application of this hood tach is. I was hoping someone here might be able to help out. The housing appears to be brand new and has a GM number cast into it. The tach itself appears used as you can see it has blue paint overspray on it and the harness has some weathering to it. Any help would be appreciated.