My 78 does not have delayed wipers. I would like to know if it is possible to convert to a delayed wiper system and if so what items are needed to purchase to complete the upgrade. Also are the proper electrical connectors already in the wiring harness or are modifications needed to complete the electrical hookups? Thanks

You can get aftermarket delay units. Some are nice, some are awful.
To switch with factory stuff, you need the switch, new wiring added to the harness, and the wiper motor cover with the delay unit. Some versions require a different wiper motor as well. Check with a parts supplier, and see if the delay unit and non delay unit have different numbers. Autozone can tell you that.