All 66 had 2 speed(fed regs), you need the motor(same til 72), switch, & small harness w/two extra wires. Get a rebuilt motor from Advance, tell them 2 spd & trade in your single(they can't tell the diff)as a core. I have sold the extra setup I had, but there is a yard locally that has more I'm sure. I added 2 spd wipers to both my 64's, you can get washers also w/this upgrade. Brian
