What size is the stock gas tank?

Cant remember how many gallon the stock tank is.....

i think 12 or 13

which one? i think its a 13

14.8 us galons short bed
12.3lmp galons cab pluss
long beds 17.4 us galons
14.5imp galons
if this helps

i have a cab plus, what does the lmp mean?

dont know that just what it saies in the oners book