The wiper switch is different from 63 to 64. The difference is the slider lever. 63 is rounded, while 64 has corners.
I have a good switch, either year. email me at firstname.lastname@example.org
A slight correction to Russ' reply. See picture below. The windshield wiper switch with rounded slide control was used throughout 1963 and into early 1964. A squared head was used from early 64 thru remainder of production. Per my notes the switchover took place sometime between VIN 64x021717 & 64x045174. I also have both type switch in VG condition for $35.