Options and color schemes
The level up from the base added a 5000 BTU propane heater. The fancy level added a 3-way power (AC/DC/LP) refrigerator (in place of the icebox) along with an extra battery and an AC/DC power hookup kit.
The final set built on that fancy level, but also had a set of overhead bunks which fold out and lock together to sleep two more adults. They are well hidden, so your truck might just have them even if you don't know it. Go out and look -- those snap covers along the sides of the camper might just conceal some steel pipe, interlocking U-channel and canvas cots! See the interior shots on the Photos page for reference.
All the trucks I've seen have either had the fridge, or the fridge plus upper bunks options. Some have been gutted and had the interior re-worked along the way, so it's hard to be sure. I suspect that, as today, most Chalets sold had all the options and gadgets possible (drives the price up don't you know. Try buying a truck today without power locks and windows.)
The camper option also included a front bumper mounted spare tire carrier and incorporated a rear step into the rear bumper to aid access to the rear door of the camper. The Chalet is about two and a half feet longer overall than a regular Blazer, due to the front mounted spare tire carrier and the overhang created by the camper itself.
The Paperwork page has scans of the original Chevy and GMC paperwork, which have more detail on weight and dimensions.
Power train options are just like any other Blazer of these years. The vast majority of Chalets came with the TH350 automatic transmission and the NP203 full-time transfer case, though there are a few SM465 manual transmissions with the NP205 part-time transfer case. (Note that many '203's have been converted to part-time with a kit and manual locking hubs.) Many of the campers came with the 400ci V8 (instead of the base 350) and most came with cruise control, air conditioning, and whatever other gadgets GM could add to boost the price -- I see sales tactics haven't changed in thirty years!
While all internally and mechanically identical, the 1976 and 1977 model years, and Chevy and GMC variants, are all cosmetically slightly different. I've assembled some thumbnails of what each iteration should look like. Please, no flak about my PaintShop skills, or lack thereof ;-) The colors will vary with different monitors and are just representations anyway -- I don't know that I *want* to have a "burnt orange" on my computer! This can also serve as a spotter's guide to determine which brand and year you're looking at, if nothing else just from the decals on the camper shell.
It does have every color combination I know of; obviously many of the trucks have been repainted, but should you see one I don't have here, lemme know. Note that 1976 trucks all look the same (Chevy and GMC only differ in decals) and only for 1977 was there any variation in color.