someotherguy
Truly Awesome
It's just evolution of the design. Of the "big three" Ford is probably the worst about parts compatibility across years. The 1988-1990 GMT400 clusters are very similar and in general, are drop-in replacements across those years. There's the difference of idiot light vs. actual gauges (requires different senders.)
Then in 1991 the pinout changed in the connector but the connector style itself and the design of the cluster LOOKS the same, but it isn't. SOME 1991 trucks got the tach cluster with needle gauges. You can swap moonies and needles in a 1991 - with clusters from another 1991. If the cluster came from a 1988-1990, you have to move those wires around in the connector for it to work. Hope that clears it up.
And then what I said about the speedometer.. since all three years of that cluster design have the calibration done on-board in the cluster. It's not difficult, just somewhat less straightforward of a modification like the DRAC module used on 1992-1995 trucks. On those years the calibration is done in that external DRAC module so the clusters (at least 1992-1994) are direct swaps with few exceptions. (Gas vs. diesel, and V8 vs. V6)
Richard
Then in 1991 the pinout changed in the connector but the connector style itself and the design of the cluster LOOKS the same, but it isn't. SOME 1991 trucks got the tach cluster with needle gauges. You can swap moonies and needles in a 1991 - with clusters from another 1991. If the cluster came from a 1988-1990, you have to move those wires around in the connector for it to work. Hope that clears it up.
And then what I said about the speedometer.. since all three years of that cluster design have the calibration done on-board in the cluster. It's not difficult, just somewhat less straightforward of a modification like the DRAC module used on 1992-1995 trucks. On those years the calibration is done in that external DRAC module so the clusters (at least 1992-1994) are direct swaps with few exceptions. (Gas vs. diesel, and V8 vs. V6)
Richard