That's nonsense and you know it. I took the OP at his word, he hooked them up backwards meaning somehow he got 2 different size terminals "hooked up backwards" He never said he just touched them to the battery. I was just wondering just how that could happen, nothing more.
Oh, and the pos. battery post is the big one so the neg. terminal will not slip on it.
If we can't ask a question or make statements then whats the point of the web site ?

 

Ok buddy...

 

My dad while the truck was parked at his place, noticed what he thought was a backwards hooked up battery.
Decided to switch it, I drove it and it killed the lights.
The next morning with light, I looked under the hood to inspect and take the headlamps out and noticed the mistake.
After switching lights to new ones and hooking battery back to positive ground. The headlamps still blew out. Truck starts fine, all other electric that worked still works.....where should I start?

 

you might want to start your own, new post for visibility....and give a clue as to what you're working on...

start with explaining what you mean by "positive ground"? I haven't seen a positive ground system in a long time. Negative (-) battery lead should attach to engine block...it is usually black in color. Positive (+) should connect to front large lug on solenoid...this is assuming you are working on a 73-79 ford!

If the pos and neg cables were indeed switched, something would have fried so I'm not sure what got changed...

as far as headlights "blowing out" have you tested the bulb with a meter and confirmed absence of continuity? As these trucks get older, higher current loads cause the circuit breaker in the headlight switch to open and close. Also the dimmer switch can get corroded/worn where the lights will appear to go out all at once....