5.2 engine

You should be fine as long as you have a tow package or reese hitch etc. really your only limited by the frame strength cause if u pull a 15k trailer and slam on the brakes it may bend your frame. but these trucks can pull around 10k, i've pulled at least that much with my 5.2 (granted to keep it at 65 mph i had to floor it almost constantly). Your horse trailer i'm guessing is only 4-5k so it wont be hard on your truck at all. hope this helps!