73-91 wiper switches ? Pulse ? Intermittent ?

[67Cowboy]

I have a '76 GMC 1 ton and my wiper switch is on it's last leg: so I want to up grade to the intermittent style switch like came in the later model trucks. I think they started in '78 and went through 91. My main question is this: is this a plug and play swap or do I need to jockey some wiring around ? I believe the 73-80 motors are all the same and the switches starting in '78 came with the round (adjustable) knob as apposed to the square knob on the other models. ANYTHING HELPS: I tried using the "search the forum" thing but it isn't working !!!