I believe it will. There should be no recalibration required with different speedometer gears. (That’s already done for you internally to the speedometer.) However... The 150 mph speedometer gauge needle will be different that the rest of them in the 79 cluster.
Not from the VIN code. If you don't have a build sheet... Look at the floor under under the console. The transmission hump would most likely show signs of modification if it was originally a manual transmission car.
First of all, great idea to remind me to look for my build sheet (I stashed years ago) Found it There it is, M21 4-speed trans
It’s still a head scratcher why this car has a 2 piece speedometer cable w/ a manual trans and NO cruise control
Sent speedometer out for rebuild—-still bouncing. Thinking only thing left is to replace lower cable. When my engine was out, it looked as though the lower has to be replaced with casing—-has anyone done that?