Battery cables getting hot!

I have a 1989 GMC K2500 SLX 4X4 automatic with a stock 350 in it and about 289,000 miles on it Just recently I was driving it on my farm and turned the truck off. A few minutes later I turned it back on and saw smoke coming from the hood, I jumped out after turning it off looked under the hood and didnt see anything wrong. Hopped back in the ruck and tried to start it and it wouldnt even turn over and the battery gauge showed nothing. Once again popped the hood and started feeling of the battery terminals it and the cable were so hot they burnt an impression on my hand.

After much tinkering I have replaced the battery, the negative battery cable(started to replace the positive cable but I traced my hand down it and didnt feel any bare spots) the alternator and all regular matenance since it has been sitting and nothing seems to fixe the problem.
I can get it started now with a charged battery but the cables still get hot and when I turn it off it will n ot start back because it has completely killed the battery in about 10 minutes.
Thanks for any suggestions
Joe