I just turned 63, getting out from under the dash is very difficult for me already, I'm afraid by the time I get to 75 (if I make it that far), even considering getting under the dash would probably be a deal breaker. I paid someone to change the heater core in my 96 Dakota a couple weeks ago because I didn't want to have to remove the dash.

Years past, I wired up an old 2 speed wiper motor with an off-on-off switch. one on was low speed, the other on was high speed. The problem was when you turned it off, the wipers stop immediately, they would not park. It took some practice, but I got pretty good at having them stop at the end of the stroke. A Dakota has 4 wires to the motor, the motor grounds through the switch. One wire is power in, one is low speed to the switch, one is high speed to the switch, and the last one is for park position (I think its momentary power after the switch is shut off) but I don't have the book with me right now. Gene