They are nearly a direct fit. You might have trouble with some of them going in because the circular shaped board that the LEDS are mounted to is sometimes not concentric to the bulb holder. It can make it hard to get it in the bulb enclosure. I also found a few that had flaws from the injection molding process. Make sure you check the portion of the bulb holder that cams onto the circuit board. They are still usable you just have to remove some flash that is leftover. They already have a resistor so you are good to go. If you want to save some time, when you have your HVAC out use a multi meter to find the positive and negative sides on the circuit board. I think someone may have some pics they took of some symbols you can look for on the board, but I had trouble finding them and did it by guessing. I should have just pulled out the meter and checked.