Under dash wiring connectors

You didn't tell us the year & model of your car. Most connectors are termed variously "56 terminal", "Packard 56", or "GM/Mopar connectors". Google and ebay for more info. If the plastic is good, you should be able to clean and bend the metal contacts to get good, solid connections. I then smear silicone di-electric grease on them. The unique connectors are the ones for the bulkhead, starter switch, wiper, headlight, and column. You generally must rob a junkyard car for those.