Yep, yours, like ours and many, many more, use (and some still do) drum drum brakes. They work just fine. The "S-Cam" thing is sometimes more noticeable on some than others. It doesn't always happen. I cleaned and lubed mine oh, about 4 or so years ago and, I kind-a expected the "clunk" to return but, not happening yet. That's alright, I got enough to keep up on anyways.
As for your "Slack adjusters". Those are attached to the actuation arm/shaft that actually rotates slightly to move the S-cams to apply the brakes. They are also attached at the top by a rod that comes directly out of the center of each brake can. Based on the design of those slack adjusters, there is a pivotal arm that's also attached and, as your brakes are applied, that pivotal arm can move adjustment gears inside the slack adjuster, IF there's enough action, to move the gears, based on the travel distance between the shoes and the drum.
If there's enough room for the adjustment gears to actually move, they go to the next gear tooth, inside the slack adjuster and stay that way. But, again, depending just how a driver of an air brake equipped coach drives his coach and, how and when and how often he uses either the e-brake or Jake brake, slack in the adjusters can become quite extensive.
The cure is putting harsh and heavy pressure on the brake pedal while imobile a few times. If there's adjustment to be had, that's when it will take place. Good luck.
2004 ITASCA HORIZON 36GD, 2011 GMC Sierra 1500 4x4 Toad '18 Honda Africa Twin Adventure Sports DCT
Retired-29.5 yrs, SDFD, Ham - KI6OND
Me, Karla and the Sophie character, (mini Schnauzer)