Hi,
I was installing a B&M floor shifter in my '68 and when I went to hook up the back-up lights, I shorted a small direct positive wire from the battery to the oil pressure coiled wire wrapped around the tube. Now I have zero juice to the fuse box. Of course it won't start, no head lights, dome light, etc. I traced for an open circuit on the small direct positive wire and it's not open. I also traced the wire that goes to the outside fender wall terminal and it's not open. Fuses are not blown. Couple of questions; where is the first place to look and what should I look for?, what is the terminal mounted on the passenger fenderwall used for?, there's a mess of bad wiring under the dash and in the engine compartment but I really didn't want to spend a zilling dollars on all the harnessess at once, which harness should I start with based on the problem description? Why didn't I disconnect the battery before I messed with the elecrical !?! It's painful to "push" it back in the garage!
Thanks for your assistance?

sounds like a fusible link that let go. I would start looking at the distribution block behind the battery. Use a test light and you'll find it.

There are 2 fusible links that could have blew, one is at the junction block behind the battery ( it is a 14g fusible link), the other is at the horn relay. (it is a 16g fusible link) The one at the horn relay should have blew first as its the smaller of the 2 but check both. Replace with a new fusible link. This is what saved your harness from melting and catching the car on fire when there is a direct short to ground. You can get one at any auto parts store. Heres a pic of where the fusible links are located.

http://www.madelectrical.com/images/chevym1.jpg

If the horn blows (assuming it worked before) then it's the link by the horn relay, if not, it's the one by the battery

I appreciate everyone's response. Ended up being nothing to do with the short I thought I caused. It was an open wire (twisted together) coming out of the starter when it was cobled for HEI. This site has excellent information and sure saves on the learning curve.
Thank's again!