neutral safety switch

On the older cars the reverse switch was on the gear shift - either on the column or on the floor shifter itself. To change over to the later style you need to locate the wiring for the shifter operated switch and wire it to the lead on the three prong tranny switch. A wiring diagram would help you a lot needless to say -

I did this on my 66 since the shifter switches on my stuff were all junk anyway. A later model trans wiring harness will make this a slick install as well.

Evans wiring harnesses made me up a nice new three prong harness to work with this stuff.