Jerry, here is my standard reply to the towing question. It is from a 69 resto pack from Chevrolet (thanks for that info Longhorn Man
). It shows what your truck can pull depending on engine, rear end ratio, etc.
6k, it must be a big boat! My gut feeling is that you will be fine pulling it with either truck, and I always err on the side of caution.
Squint and you can read it
Edit by me;
I forgot to mention...Brakes! On a load that big you will need brakes on the trailer (at least one axle). That means you will need wiring and a electric brake controler. Pulling it is the easy part, stopping it is the challenge.