Re: ATF: Big Country - Model of King pin box
I had the same question a couple days ago. Called Heartland and the guy I spoke to suggested I call Lippert! Somehow this didn't compute, since they make a lot of pinboxes and I wouldn't expect them to know which ones Heartland installs on which trailers. But I did talk to Lippert - and they were a big help. They linked me to the manufacturing drawings of the different pinboxes. It was easy to compare the drawings to my RV (Cyclone 3210) and figure out that I had a Lippert 1621HD pinbox. I suggest you do the same, and you'll then be certain of the answer.
By the way: I'm an engineer, and don't understand how an air hitch or air pinbox can do much for ride quality. The air suspension units damp VERTICAL motion. The problem with hauling a big 5'er is fore and aft horizontal forces, usually called "chucking". The only pinbox I've seen that is designed to take that out is the Demco Glide Ride. I've got one that I ordered last week, that just came in today, and will know by the end of the week if this is the solution. Personally - I doubt an air pinbox will do much for you.
If you want to wait a few days, I'll report back on the forum.
Don Hutchins