LED bulbs for dash lights

I use them in my A's and 80's M-B cars. You can't dim them very well, but I need all the light I can get anyway, especially in the M-B where I could barely see the speedo at night before. In theory, they should last forever, but I had two 1156 ones that looked cool w/ big heat sinks but failed in 1 sec. One dash bulb has started coming and going, but could be a loose connection. Another advantage is they won't melt the blue bulb surround in an A, or otherwise degrade the dash plastic like a hot incandescent can. Even with the same bulb#, not all physically fit. You also must look close at the terminal. One type fried a trace in my M-B dash because it bridged the holder, but that is more due to the different M-B holders (look like Mopar 1/4 turn, but differ).