If you’re not using a donor car and have purchased all new parts for your “donor” parts list, it is likely that you are missing this part.  This plate is not included if you purchase a new wiper motor from the dealer and as far as I can tell, the only way you can purchase it new is if you buy the entire wiper assembly for a C5 Corvette for a few hundred dollars.  This park plate is necessary to allow the wiper linkage to correctly go into the “parked” position after you turn off your wipers.

This plate mounts between the FFR aluminum mounting plate and the wiper motor itself.  In my experience, the new wiper motors do not have one of the screw bosses that secure this plate to the wiper motor, but the plate does install over some “studs” on the wiper motor, so this is not a major problem.  Without the screw securing the park plate to the motor, all that is required is a couple strips of foam weatherstripping to hold the park plate up against the aluminum FFR mounting plate so that the park tab ends up in the proper position…..see photos for details.