Hi Guy,

I am currently the proud owner of a 2003 Monte Carlo SS Black on Black and absolutely gorgeous to look at, I found this forum because I was looking for advise on my rear window defogger not working, I reed about the melted connectors and wires. I literally tore out the entire interior, minus the front seats and carpet, found all my wires and connectors good, I ended up finding a poor connection between the curate breaker and the fuse box (pictures posted on the tread) one day later, no rear defogger AGAIN, i go to the fuse box wiggle the breaker around and it works again, out comes the volt meter, I have 14.28 volts at the battery. 13.89 volts going into the fuse box, and 11.29 volts at the grid .... wtf... back to the box I have 13.79 going in, but only 12.01 coming out, so I am loosing a volt and a half in the box, obviously a bad contact in the box, and the cherry on the cake is that can't find an aftermarket fuse box yayyyyyy chevy

 

I had to replace the breaker in my 04 Monte and ex-wife's 05 Impala. In my case, the breaker rattled, it was definitely dead. I got one from the local parts store. I could not find a direct replacement at the parts store. The blades on it were wider then the what would fit into the block. I had to use the Dremel to grind them down to fit.
At some point, someone claimed the correct part is this (but I never followed up on it):
30a breaker is part #MNB30