Technical Attention GM gurus! 70's GM Tachometer? ID Help

Hello,
This looks like alot of the 70's early 80's tachs but I can't find one that's exactly like it. The 2nd photo is the piece that's on the back. Any help would be greatly appreciated. Thank You

 

7240 looks like a standard electronic component date code: 1972, 40th week

So it would be an early production 1973 Monte Carlo tach.

 

Thank You