This page has a whole bunch of pictures, so if you're on a slow connection it'll take a long while to load.
Here I've assembled some pictures of other brands of slide-in pop-up camper shells and such on various brands of trucks, that resemble the Chalet. See the Links page for URL's of the various sites mentioned.
This is the Toyota Chinook camper, a close sister to the Chevy. Pictures are from the Yahoo Group for these trucks. Notice how this camper replaces the bed of the pickup, rather than sitting on it as the Chevy. Nonetheless, the pickup cab is still open to the camper inside.
Chinook also did van conversions on the van cab + chassis offered by Chevy. There's a Yahoo group for this one, a 1971 Chevy van by Chinook.
This one's actually an 80's Blazer, but done so well I had to include it. This is a home-made camper shell, from one of the folks on Colorado K5.
These would be Chevy's offerings then ... and now. From Four Wheeler magazine (dated March 1970) we have the prototype Blazer Sports Camper (left), and on the right we have 2002's "Avalanche Base Camp", a camping version of Chevy's much-maligned Avalanche sport-utility-pickup-crossover thing. It doesn't actually have a shell, just a tent that folds out of the bed/cargo area, but it's interesting to see that Chevy keeps testing its feet in the water of the camping market.
And here we have an assortment of other brands of campers installed on different vehicles. I don't have any further information on these campers (they seem less common than the Chalet, frighteningly enough) so if you have any details, feel free to share them! From left to right:
Here's some pix from a 1977 article about Four Wheel Pop-Up Campers. You can read the article itself on the Paperwork page, close to the bottom. From left to right, here are campers on a second generation Blazer (without half-cab; the camper mounted directly to the truck), an International Scout, and an early Bronco.