My car is a 1968 Firebird convertible. All original. I have it all taken apart so the wiring harness I had rolled up in a ball and sitting in a bucket. The switch is in a bucket of small parts somewhere. My 1968 FSM shows the Firebird switch connector I posted, but the sheet for the Tempest shows a connector shaped more like an "L". On that one the offset terminal is black for ground. The two blue ones together are for the high and low speed, so as you said, if wrong just reverse them. EDIT: Looking at the wiring diagrams I think the wiper is what we call a 'negative switched' system. That means the wiper motor is wired hot, and the control switch grounds the circuit. So if you have the loose blue wires you can simply power the wiper motor by turning the ignition key on, and touch the loose wires to a ground one at a time. One will be slow and the other fast.