Outer Limits 4x4 Board

Now what i have done is taken the dash out of a 85 sr5 extracab and put it into my 85 dualcab that had no tacho. Now the question is the loom the same or are there lees wires on my loome? I want to get the tacho working but im now sure where to start?

Everything else works on the dash except the tacho.

For a start, you need to know if the new dash is from a petrol or diesel engine. I know in the next model after yours, you can't mix them, as the tacho signals are different.

sorry both truck are 3y petrol