3588587 and 72 Demon

Hi Folks, I am trying to understand the (I think) seat belt relay in my 72 Demon. It is part number 3588587. I no longer have the original front seat for this car. And I thought it was just a buzzer that is set off by sitting in the seat until you buckle up? Is that correct? And if so, I don't remember if it prevented the car from starting but I think it just buzzed and drove you crazy. If I wanted to discontinue it and be sure the car will still start, how should I approach the fix? Also, I changed out some dash parts and now I seem to have a 3 speed with delay wiper switch but the car came with only a 2 speed motor? However, the 3 speed switch plugs into the harness and I picked up a 2 speed switch and it does not even come close to the plugs going together? My build sheet wiper motor option is left blank? So I assume I have 2 speed. my 2 speed does have a small accessory ceramic plug on it. Could it be a delay wiper? I also know the car had a foot pump for the washer bottle??