Dash harness meltdown help

That wiper switch is one of several that mopar used in the 1960's that all had that large round housing. My 64ragtop GT has the variable speed wipers, and the rheostat is in that housing. The rectangular box on the flying arm is a circuit breaker for the backup lights, windshield washer pump and wipers. The wiring for the single, two speed, and variable wipers are shown at the top right, and bottom right on your instrument cluster wiring drawing in the F.S.M. Here's a good look at mine: ATB BC