Bought an electric wiper motor for my 1959 Apache, I really didn't like the knob for the switch and wanted to refit an original knob to the switch. New switch has a round shaft, original vacuum motor switch has a 1/4 inch hex shaft. I had seen pictures where someone cut-off the vacuum switch shaft and used that to convert to the original knob. I didn't want to damage the original vacuum switch so looked for another way. I found at McMaster Carr Part Number 91780A184, Female Threaded Hex Standoff, Aluminum, 1/4" Hex, 3/8" Long, 10-32 Thread. These fit the new switch knob perfectly, but I needed to slightly enlarge the inside to fit over the switch shaft by drilling. I then drilled a hole in the side of the hex to tap for a 6-32 set screw. I slid the coupling on the wiper shaft, screwed the set screw to the shaft and then with a cut-off wheel took off the exposed set screw. I then slid the original knob on and tightened its set screw. Looks a lot better. Pictures below.
