Tremec wiring problem...what have I done!!

Ok... I drop in a new motor in my car. Took out one busted V8 and replaced. The Tremec tranny was fine and dandy. Get all back together and car has a crazy ass electical demon associated with reverse. The car used to be an auto 4cyl, but thats beside the point cause every thing was fine before. Any way. Car runs and idles fine. Letting the clutch out causes some kind of electical spike. And putting it in reverse or even trying to, causes the end of the world!! Metal on metal grinding and rubbing what the hell is going on tranny was fine. I also tried getting in reverse gear first then starting it. Holy crap she was pissed. No power to any of the car except the starter which started itself in just the on position, didnt even get the key to the start position yet. And one time it started in reverse and it sounded like all sorts of loose metal in the tranny whipping around even with the clutch in. So I figured my tremec has some how **** the bed. So just trying to end this wierd electrical **** I undid all the harness to the tremec. Now its fine. And goes in and out of reverse fine and shifts through all gears. What the hell is electrical inside a tranny that could have been getting messed up. Which wire did I have on backwards? I remember something about a magnet or something. What are the connections? The one on the body and the one on the tail shaft?

well right now everything is disconnected and its fine. Except no back-up lights. But what wiring problem could make the tranny itself freak out. I still have this crazy surge when you step on the clutch though. I def cot some kind of electrical problem.

Thats it! its got to be. I was too freaked to ever think of that. Thanks man. Now I just have to figure out what the hell the electrical problem is. This time around I hooked up more grounds and got the car running better. Thats probably what make this harness come to life, which was probably always messed up and I never knew.