Bob,
I could be all wet here as I'm not real familiar with a '58 and may have the wrong picture in my head. I visualized the wires being factory staked with rivet type deals onto the back of the fuse block. I thought all the wires exited from the rear and only the fuses and fuse holders were visible from the front.
My point was that if it isn't a device where you can attach new wires conveniently to the fuse holders, then you have to clip the factory attached wires and splice your new wires onto those! This gets things cluttered and isn't clean looking.
This might be much ado about nothing. If you have screw attachments or push on connectors, you're home free. Sorry for confusing the issue.
Stuart
