I do have a PDF called: Jeep YJ FSM Wiring diagrams. It must have been put together by someone, and I don't know where I got it. But it does have the '87 dash schematics. Just not the speedometer, I think because it was mechanical in '87. It has info all the way up to '94. So maybe you can use a newer model speedo schematic. PM me if you would like it.

 

I believe it was a mechanical speedo.
hoping Mr.B could give this quick check
I do not have a way to double check my diagram -

 

I can't even read that. I can barely read the one I have. But here it is.

 

This is what mine were on my '90. Disregard the pin #'s as though are where I put them in a 12 pin Molex connector and the gauge color is what I ran in my home built harness. The speedo only has a cable and lights, the tach should be very clear once you pull the gauge.

 

Thank you very much for the responses.

 

If you're having trouble reading that, PM me for the link. It's easier to read in PDF form.