in response to a message on the Corvette Forum # 313159
.1968-1972 location and picture of wiper door solenoid & electrical relay

The wiper door solenoid can be viewed while lying on your back looking up under the dash. It is about 2 1/2 inches long and is illustrated as item C in this illustration. The electrical relay for the wiper motor mounts under the shifter console. It is about the size of a pack of cigarettes and is illustrated as item M in this illustration. Note this same relay is used on later models as a blower motor relay. Always check the number and orientation of the bayonet terminals when replacing these relays.