When I installed the GP dash, it didn't have the dash mounted wiper switch, being a later model dash. I have since added a later tilt column with a pulse/ delay wiper switch. I've also installed the later wiper motor, which I like better, and seems to work more efficiently. The delay function seemed to work okay, but the wipers operated too slowly for my liking. Adding a relay was the solution. Even the washer pump works more efficiently.
To install the later wiper motor, you'll need to source the pigtail / plugs from a later year G-body. Also, the bolt pattern on the wiper motor is slightly off, which entails drilling a new hole so all three mounting points line up.