When they tested your batteries did they disconnect them? or at least one of them? If not you could have one good battery masking a bad one since they are hooked together in parallel.

 

I noticed that someone said that 13.2 volts means your battery is proper. This is incorrect. 12.7 to 12.75 (theoretically 12.8....but I've NEVER seen a 12.8....ever) is the no load voltage of a GOOD and FULLY CHARGED car battery. And it goes down from there...depending on if it's bad...or not fully charged. By the way,...you "might' get a 13.2 volt reading if you've just shut your truck off and not let the batteries get back to their normal state.. Give it at least ten minutes.

 

Actually, if you want to be technical....give it 24 hours before taking a reading... I never do..I just give it a little while.