LED bulbs

If you install them backwards, they simply don't work, so nothing you did. Some expensive ones may work either way. Presumably, they were rated for 12 VDC use. Pishta is talking about designing your own assembly w/ raw LED's. I use LED's several places. Dash ones help a lot in my M-B cluster where the LED's shine forward into the "light tubes". I use in my A's too since I don't like melted plastic from incandescent's and shouldn't have to change ever. But, they don't dim as well. I did have a problem where some LED's bridged the bulb holder in my M-B and caused a short circuit that smoked a cluster trace. The M-B holders look like Mopar, but connect slightly differently, and shouldn't be an issue in a Mopar holder.

I use LED's in some tail-lights, especially for running lights when I have multiple bulbs and figure an LED will give a better chance of lasting forever even if dimmer (some light is better than none). Like you, I tried some ebay ones from China that failed in ~1 sec. They were real neat-looking w/ integral brass heat sinks, and surprisingly cheap (~$2 ea, wonder why). Other ebay ones from China have worked fine, other than one in my M-B climate switch started flickering recently.