Dear Bob, Les, and mid-60s Buick fans,
So seeing as I have none of that I can leave that fuse out and not worry about it.
. . . Sufferin' Succotash! I come back from a nice dinner out, make a quick check the 65GS.com forum, and the next thing I find myself doing is crawling on my elbows trying to take a picture of my trusty wagon's fuse panel!! . . . 
Sorry the picture is lousy but does appear to show that my wagon as the circuit breaker installed:

More mysterious is that it appears to have been replaced from what I remember it. The old one was all metal. So can you get these circuit breakers still? If so, is there any reason not to replace it?
Curious minds want to know!

Cheers, Edouard
