you probably shorted out the power cable to the starter. mostly likely very near the starter. i have had the same thing happen by shorting it out against a header that had melted the insulation. should be pretty easy to fix. just follow the lines going down to the starter and look for the damaged area. if you dont mind spending the time and money, and if this is where the problem is, you might consider dropping the starter and splicing in a quick disconnect starter harness (got mine from Sumitt but i'm sure there are other places that carry them). it is a great way to replace those wires near the starter that are often baked out and brittle, with nice new ones. also it makes changing out the starter a bunny in the future. i also added a starter heat shield but with a six you may have plenty of clearance and that may not be needed.