I used female push on connectors on 3 of 4 terminals and soldered 1 of them. I mounted mine a bit different in the case than that pic, its a tight fit mounting it in the Chrysler ECU. I totally removed the old circuit board, leaving the plastic connector backside and the terminal pins. I hade to epoxy the backside of the plastic connector after soldering the wires to the pins. After the epoxy cured I used the Right Stuff rtv to seal up the back of the plastic connector. The factory ECU case is a good heat sink for the GM module, just use the white paste heat sink compound not the clear silicone paste that some use.