97 12 valve melting batter terminals please HELP!!!!!
 

OK so the other night I went to get my son and as I was heading to the house I lost all my lights cluster everything so I pulled over and the truck died and smelled like burnt plastic piped the hook seen nothing tried to start it and it had no power at all so I replaced the battery's it need it and when I went to hook them up it started melting the terminals as soon as I touched the cable to the terminal

From the sounds of your situation you have a short to ground on the power cable.

I would start by pulling the cables off the starter, hook the batteries up and see if the issue is still there. If not then it is likely a shorted starter.
If it is, unhook the alternator. Same thing.
Still there? Try the grid heater.

If it's still doing it I would be chasing those cables to look for a rub spot onto the frame or engine, or any place the positive is making a good ground contact.

Let me know what you come up with!
Good luck,