I recently replaced the next gen front seats in my 2015 Model S with 1st gen seats. The first gen seats are much more comfortable for me. Tesla makes adapters you can buy over the counter to swap the next gen seats into a 1st gen seat car, which makes it very easy. Unfortunately, if you want to go in the other direction, you're on your own. I bought a nice set of first gen front seats. Since I wanted to sell the next gen seats to recoup some of the cost, I couldn't cut the connectors off the next gen seats. So I got on ebay and bought the complete next gen seat wiring harness for each front seat and cut off the connectors I needed. Now that I had the connectors, the big question is: which wire connects to which wire? The diagrams below show how it should be connected. I also swapped the memory seat module (MSM) from the next gen drivers seat to the 1st gen drivers seat. You will also need to get the correct next gen airbag connector and connect the purple-orange, white-orange, and brown wires.