I got into this type thing today , I bought a Komatsu D39 with cab , had all components but the actual head unit for stereo. Dealer wanted 500$ for a radio , my PSR told me to get an aftermarket it would fit right in etc. Come to find out the power source in the plug was 24volt. I went to radio shack and picked up two of the 7812 . I was told by a local automotive electronic specialist that they would not work , would burn out fast etc. I do have the heat sinks to put on them. What's the longevity of these inexpensive little boogers?