Right you are. That wire "everyone" speaks of didn't show up on untach'd models until 82, I think, with the new dash. You should have it on your 83, but as yours is a GL it came already attached to a tach! The + end of the coil? That is not correct-- someone slipped up there; should be minus like you say. The car's wiring already runs that lead inside to the fuel pump relay, so it is possible to hook up the tach without leaving the comfort of the cabin -- an advantage I found well worth taking yesterday while adding keyless entry to my daughter's '90. Brrrr.
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Art Benstein near Baltimore