Thanks for all the help, got my instrument cluster off very easily. Need a little more help. I am also adding the turbo cluster, don't have the harness/senders yet though (looks good even unlit)

I am going to assume that the previously unused two-prong female plug goes onto the two male prongs at the bottom of the tach. It's a red wire with a blue plug. Am I Right?

There is also a large unused "spade" (?) on a thick gray wire. What is this for?

Also unused is a very long (paired together) set of spade plugs, one small and one large. Where do these go?

Again, thanks for all the help. - Mike

Hey man
I'm in the middle of doing the exact same thing in my '83. Helps me to know that you also have a gray wire. I've had many posts about this earlier this month, if you can find them with the search. Basically i haven't got mine to work yet, but i did this whole conversion to my dads '90 240 in about 20 minutes last night.

The tach gets everything it needs from the board when you mount it, except the signal, which i now believe is the gray wire. In my car though, this gray wire now goes nowhere. Check on your coil to see what wires are on there, there should be one that matches this gray wire on the negative terminal of the coil. If not, run a new one down there. (that's what i'm doing tonight). But basically, just one wire goes onto the little spade connector at the bottom of the tach.

I'm not sure about the other wires on the cluster, i'll take a look tonight at mine and post back.
Good luck!

Whoa, I'm jumping in late but there is no bouble connection to be made at the bottom of the large tach, even if there are two commectors there, the coil wire goes there, period. And the gray wire sounds like the coil wire in a late 70s early 80s car that plugs in there at the tach. A coil wire will fry any other connection.

even more... the two male plugs on near the tach are exactly like the ones for the circular and semi-circular black plugs at the other end of the board.

sorry, to be more specific the double plug isn't actually on the tack, but on the board near the bottom of the tach. There is a large male spade on the tach though.