I have an old farm truck, a 1972 Dodge full size with 3/4 ton rear end on it. Plus a big V8 engine. We had the motor rebuilt, and just about everything replaced. I used it for a long time to pull a horse trailer and everything else.
I think if your wanting something to just haul horses, your better off fixing the old gal.
I love my old Dodge, I don't think twice about dumping a load of rocks or manure in the bed or driving it across a pasture. A new one....not so much