42RH / A-500 in a Duster with pictures.

OK an update- I'm tinkering around with schemes for shifting control and tried a vacuum switch for the kickdown. Don't like it as if you get the throttle just right it will cause the car to rapidly shift in and out of overdrive even after playing with the set points.. My initial thought was this is perfect time for a WOT switch but went with vacuum as it can be hidden and was fairly quick to do. I'll play with it a bit more but think when I have the spare time install a Wide Open Throttle switch, either of the carb linkage or gas pedal.

If you do want to go with a vacuum switch, I found one for $12 shipped.