1966's of any kind can come with either a 1 speed or a 2 speed windshield wiper system. Here's how to tell at the wiper motor itself:
1 speed: has 3 male spade connectors on motor box
2 speed: has a square 4 pin molded bullet plug (2 male, 2 female)
The 1 speed may or may not come with a washer motor pump; the 2 speed system is configured and wired for the washer pump.
Oh, and just for the record, the 2 speed wiper system has two speeds: slow and slower. *G*