Ok looking at the FSMs I have. 1992 version shows Type A and Type B. It classes mine as Type B and yours as Type A Picture of early dash (Type B). Note that it has x1 12pin vertical plug (with tacho and oil feeding) an 8 pin vertical plug and 10 pin vertical plug. Picture of (Type A) wiring diagram
Just pulled out the collection of clusters I have. Looking at the later one, they do share the soldered link that goes to the ground on the top horizontal plug
By now you guys have busted your nads looking for answers, we feel your pain. Sorry if this sounds like an odd way to put it but I keep returning to the scene of the crime to get more clues The CD player was mounted in the dash yeah? The front bumper was replaced, different wiring to suit the lights? The new steering wheel was the same spec?