I had a problem when I found out that my dash harness was a 74 and the engine harnesses were 73. I originally discovered this mismatch when the car wouldn't fire up. The yellow start wires were mismatched (not in the same location). I believe 3 wires had to be pulled out and moved to a different hole in the plug so they would line up with the dash harness plug. I can't say how different the 71 wiring is so you'll have to take the electrical drawing for the dash harness and go through each wire to see which ones don't match up. I just made a drawing of the 3 plugs and put the wire color and name on it according to the service manual. I then looked at the engine harness plugs and figured out which ones were different colors than the corresponding wires on the drawing. I hope that all makes sense.
