[the man in black]

Mid year 2011 got the HO. It was a 68 with some "upgrades". I can't remember what they consisted of could have just been a torque convertor.
The new trucks the HO is with the aisin only I believe.

 

[the man in black]

I'd guess you have the HO based on the build date. The tailgate is also a good indicator, not sure why you assume it's been swapped.

Isn't there a way to get the original window sticker?

 

[the man in black]

Yes. Optional equipment will be in addition to or in lieu of standard equipment.
You have the HO.