Well, the plot thickens.

I retested the tach connector at the back of the gauge. I am showing 14 volts of DC power, but when tested AC, I get a momentary jump to 3 or 4 volts and then it drops off to zero.

I decided to check the only thing I hadn’t gotten around to looking at, which is the tach pickup on the bell housing. So far, unless I’m looking in the wrong spot, I have not found a terminal on the bell housing at all. I found one broken brown wire coming from the engine harness, with no connector on the end of it. If anyone has a clear photo of the pickup location, that would be immensely helpful. I haven’t found a replacement part for the pickup either, if anyone has a source.

This all made me wonder if this is the original engine and trans. I saw that there are a couple different castings for the bell housing on these cars, one smooth and one with cooling fins. My car has a smooth bell housing. That’s as far as I’ve made it. Any tips on identifying whether or not this engine/trans is original?