Ok, the Roadmaster unit came and I just finished the install. The item# on the box is 3611, and the Reference number is MK3-XXF.
I ran into one snag on the install that was a pain in the ass to deal with. The install requires you to remove the roller that sits on the top of the leaf springs on each side as it is in the way of the Roadmaster unit. It uses a hex bolt that mounts flush. On the passenger side the head of that bolt is inside, facing the spare tire, so you can't see it if you just have the truck on jack stands, and the instructions don't tell you what size hex key you need. I was able to feel around with different sizes until I found one that fit and was able to get that one off without too much hassle.
However, on the driver's the face of the hex bolt is actually facing to the outside toward the tire. It seems like that would make it easier, but actually the shocks on the driver's side can block the hex bolt almost completely so you have to play around with jacking up the leaf springs on that side to manipulate it so that it is clear of the shocks. I was able to get it fairly clear, but the bolt wouldn't come loose and the hex key stripped it out. I ended up making several trips to Home Depot to try and find something to extract the stripped out bolt. What finally did the trick was a dremel tool to cut a slot in the head of the bolt and a huge flat-head screwdriver with channel locks clamped onto it for leverage. Once the bolt broke loose it came out fairly easily. The bolt is ruined now though, so I'm going to have to figure out how to order some spares from Ford.
Thankfully I don't plan on taking the Roadmaster setup off the truck anytime soon. I haven't had a chance to actually drive it yet, but I'll update this thread after I have a chance to try it out including towing the trailer mentioned above next weekend.