Tachometer not working

[Royce]

Agree except he needs this one:

Wire Assembly - Dash to Engine Gauge Feed - 390 / 428CJ / SCJ - Repro ~ 1969...

Or just toss the whole mess and install one of these:
Wire Assembly - Dash to Engine Gauge Feed with A/C - 351 W - Repro ~ 1969 - 1970 Mercury Cougar ( 1969 Mercury Cougar, 1970 Mercury Cougar ) at West Coast Classic Cougar :: The Definitive 1967 - 1973 Mercury Cougar Parts Source