H.lights flickered and the complete shutoff

[Jchiffons]

I just picked up my first 67/72 C20 a few weeks ago. I've been working on the bodywork mostly and a few regular engine maintenance items. I replaced the spark plugs and changed the oil so far and that's it. The batter was replaced a few months ago and has worked fine until the other day. I didn't have enough charge to turn the engine over but the lights would power up. It would immediately turn over and run fine after jumping (Wednesday) tonight I tried to start and it did crank but there wasn't enough juice to turn over. I again attached the jumpers and I got an immediate turnover and start. I went for a short trip when the head lights went from full lamp to dim then then a few seconds later the lamps went dead and so did the engine. I was lucky enough go get over to the side and someone pulled over to assist. As soon as I connected the jumpers sparks started flying and the wires heated up so I disconnected. I called the wife thinking this guys cables were bad and had her bring mine over. I experienced the same issue, now after having 3 eyes review I know I had the polarity correct. So right now I'm waiting for the tow truck, what additional information can I provide for a better diagnosis?

Jim