66 gauges in a 65?

Yes, you will run into problems. The wiring will not match up. Were nothing is imposible I would recomend you get the wiring diagrams for both years a weekend and a couple cases of beer.

I figured this little problem out about a year and a half ago when I bought a 66 and the previous owner suplied me with an underdash wiring harness that did not match the instument cluster. Further investigation proved the suplied wiring was for a 65 so I bought a 66 harness.

351w_swap said:

Has anyone done this swap, I like the style better and want to put 66 gauges and bezel in my 65. Will i run into any problems? thanks

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Several years ago Mustang Monthly had an article that detailed the complete conversion. It is a great resource.

Basically, you will need to run some new wires and add the appropriate oil sensor. You must add wires for the ampmeter to function--the idiot light wiring is not enough. There is also the problem of the turn signal whereas the 65' has one light and the 66' uses 2.

The speedo cable, dash illumination lights, high beam light, gas gauge wires, and temp gauge wires will all interchange with the 66'

It is best to do a little notching of the dash, under the speedo as the 66 speedo pod is slightly taller. You will also need to rebend the dash screw tangs and add the 66' clips to make a complete conversion.