64-65 Turn Signal Switch Difference?

I havn't posted here in a couple years, been sunk with college and the stang stays at home because it's not legal. I've been working on it and I need a turn signal switch. This will be about the third one I've put on it. The contacts are faulty, the ohmmeter reads an open circut from power wire to signal contacts in all positions. I jumped the switchwith power and it lit the lights.

So my question turns to product selection. The car was originally a generator (64.5) car that was switched over to alternator. It looks like an original wiring harness was left in place (prev owner). There is a big price difference ($24 to $89) between a 64.5 model and a 65-66 model switch. I found one recipt for a 64.5 model (the last one most likley) but I can be sure I've never used a 65. Does anyone know the differencs between the two? Or why I might be going thru so many switches?

Does D. Hearn still post here?

This is my new (less expensive) hobby: kayak fishing

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Thanks. Guess I'll just have to shell out the cash on a 64.5 . Any thoughts on why the switch keeps going out?

Some Grant wheel. I never adjusted the gap but there is very minimal gap. I took the switch apart today and found the culpret. There is a brass head on the back side of where the power wire comes into the switch, a contact wiper is routed under that head to the signal contacts. Put the ohmmeter thru the head and the wire and it was an open circuit. Twisted the wire back and forth a bit and it closed the circuit. The plastic was i bit melted around the power wire, which probably explains the odd open circuit. The wires in the trunk are a little rat chewed so they may be shorting a bit.

Twice the price to replace a functioning wheel is not an effecient use of my limited funds. After I get my engineering degree I will have more room to splurge on the details.