installed new starter and now I have a short?

I figured I'd post this up in case anyone else came across this. I have a 72 with a 360 and headers. Has a reman starter that cranks slow when the car is warm and usually won't start. Starts perfectly when cold though. Someone has definitely done this job before because the header bolts were very loose as well as the starter and the tie rods. Scary...

I bought a mini starter and spent a big chunk of time yesterday installing it. Removed the header bolts and tie rod and center link and was able to get the old one out. Oh yeah and I discovered that the rear exhaust manifold bolt dumps your coolant, fun fun.

Everything is tight under there and I'm working on the ground. I installed the two electrical connections and tightened down everything blind. Long story short everything is together and I hook up the battery. As soon as I put the neg terminal on, pos is already on, it sparks and I hear some type of noise. It took me a couple tries to get it off and in that quick time the neg cable got pretty warm.

I'm positive that I didn't hook the battery up wrong. It's pretty obvious which one is the pos and neg. Neg goes to the block and firewall. Went through all that before I made the electrical connections. The only thing I can think of is that the connections on the starter itself twisted when I was tightening them down and are touching....

Any ideas? I was shot late last night when this happened and just went to bed. I hope I didn't fry anything. Thanks in advance