The whole heater box should come tree and then you just undo about a thousand small screws and 2 slightly larger ones that hold the heater core itself. Make sure you order a heater core with the metal bracket. I got the omida one off amazon. It came with the bracket. Try to salvage the foam from the old core as it just allows for a tighter fit to prevent rattling. Remove old core and replace with new. If you have any questions just ask. I did this whole repair last weekend so it's all pretty fresh.