Grand Am Grand Prix tachometer
 

Will this tachometer fit all 73 to 75 Grand Am and any 73 to 77 with that style cluster?

Bolt in, yes. function that would be the question. Keep in mind there were two different tachs for '71, 72's, & '73 model Pontiacs. One for points, one for unitized. Eventually, points distribs were no longer offered & every engine received an HEI distributer. Is there an ink stamped date & part number on the rear of the tach? have several such tach clusters mainly for electronic ign use, can pull them out in the AM, & compare.

On back side of tach ink stamped numbers 565800. Does that help identity which year the tach was used? Has a few more letters or numbers but to faint to read.

5658007 was the only tachometer part number listed for 1973-74 AH and AG models in the GM parts book.

Are all the 73 and 74 tach’s able to work on either the points or Hei? Is that wiring harness pictured for a 73/74 model only?

I would say YES.

HEI was a mid year 1974 addition, and unitized was available all of 1973.