If you have a 65 amp alternator your amp gauge better read at least 75 amps or you will burn it up and possibly the car with it. If you want to use your old wires bypass the amp gauge. The reason for a larger gauge than the rating is many 65 amp units will charge in the low to mid 70s range under the right conditions. I have seen guys try this and when it shorts out the whole wiring harness burnt in just a few seconds setting everything on fire. My advice is don't do it unless you don't care if you burn down your car,
