The stock alternator was a 55 amp Motorola 8AR2015K according to my parts book. I think 55 amps is a little shy of what it should have, especially when you start adding extra lights and monitors on. My 2-155 drops down to around 12 volts when I have all of the lights on, but we do have 3 extras. I have been thinking of finding something more in the 80-100 amp range to keep up with the extra demand. I don't know what that particular alternator costs to rebuild, but like everything else these days, it isn't going to be cheap. Do some price checking before you make a decision.