64 instrument cluster swap into a 65 barracuda harness question

My 65 barracuda instrument cluster needs help. I purchased a 64 Cluster part number 2427427 and it had 9 pins on the connection to the board. Mine is 2496508 and it has 8 pins. I ohm'd out the 8 pin board as reference and see there are a few pins that must be swapped. But thinking about this I know that the Fuel gage, alternator, and temp are all in separate spots . That is how I know to swap a few pins when I pull the cluster currently in my car. The 64 cluster is in much better shape. Is there any difference in the 64 and the 65 clusters that I should know about. The 508 board is an older spare I used to just compare and make notes with. Any insight and help would be greatly appreciated. My speedo is dead beyond repair so that is why I am swapping clusters. I need a working one to drive the car. mine also goes up to 80 mph while all the others I have found go up to 120. I have a place called Tacoma Speed that will test the one I got in the cluster I am putting in and they will also provide an adaptor if I need it. I will then have the speedo and car calibrated together.

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