will a 91 dash go into a 88

The MIL would be the check engine light, and the diagram above does not show it. I know some of the 87-89 cars had them - those with mass air and only California cars in 87. I can look at my wiring diagrams to see what color it is. Of course that is if you have the computer set up to trigger it.

For the second 12V on C250, just add another power feed to pin 7, branching off of the wire to pin 4.

I'd have to look at my wiring diagrams on the rest. I didn't want to mess with repinning the plugs, so that is why I just changed the speedo in my cluster.

Don't seem to have a check engine light so I'll go ahead and keep that one blank

I'm switching over because I really like the look of the 90-93 cluster plus I got someone to calibrate the 7k tach for my 4cyl within 30rpm so its pretty accurate

But from what I can tell there's going to be a few wires that will be cut, I have 3 pins from c250 going to the 251 plug (can't remember what they are though) and it doesn't look like anything goes from c251 to c250

And oh yeah I take it the pin used to check the lights when the key is in the on position is cut since it has nowhere to go