Bob - to my knowledge, only Landmark 365 has a Disc Brake option from Heartland.
Regardless of what Heartland brand you are considering, I'd like to suggest that you ask your dealer to coordinate getting your coach to MORryde to have them install Disc Brakes. They do a good job and the system they install is very nice.
You may have to negotiate with and pay MORryde directly, but many dealers can often coordinate getting your coach from our dispatch lot, over to MORryde, then to their dealership for delivery to you.