Tow capacity, Electric brake box inside truck,tranny cooler?

If you get anywhere close to 13,200lb, I'll give you 100-1 odds you are over your payload by the time you get ready to roll. The hitch weight alone should be somewhere around 1600-2000lb.

Check the truck, you probably already have a trans cooler and brake controller (if it fails, you can always do an after market one to get home but they work pretty good)