Dead Battery: What the Heck am I Missing?

[swissarmychainsaw]

1975 GMC 350/350 pickup
had it about 6 months, daily driver. When I bought it I put in a Brand New battery from O'reilly's

Yesterday it's a bit misty in the morning so I turn on my lights on the way to work. Yeah, I never turn them off.
Battery was totally dead, no dash lights, idiot lights, etc.

So at night, when I get off work, a buddy gives me a jump.
It takes a minute but I get it fired up and drive it on the fwy about 30 minutes home.
Park at my house, and shut it off. Decided I should pull up in the driveway and go to start it. DEAD.
No lights of ANY kind. FLAT DEAD.

HRM. ok. Pull it out, bring it to the garage and Put my Battery Tender 1.25A (for a motorcycle) on it and let it sit overnight.

In the Morning TOTALLY DEAD.
Battery Tender shows the red light (as in charging, but below 80% full).
Try and jump start it with the wife's car, no dice.

I say "hey this battery is junk" and take it to the store.
Dude tests it, says this battery is good but needs a charge.
I say, man, I don't think it is!

He charges it (during the day) tests is and says "good to go".

Bring it home, put in truck. SAME THING. DEAD. No lights at all.

Volt meter shows 14v.

Is there a main fuse I am missing somewhere?

I'm stumped.

The fuses look all ok. (thanks for putting them under the dash like that btw! yea!)