Although I don't think I've ever seen a GMC version before. Makes me wonder if it is original, restored, or a conversion using Chevy parts.
I have seen the gmc, it's not called chalet but Casa Grande
Correct, GMC Jimmy Casa Grande. This one is #1457, built in 12/76. Essentially identical to the Chalet, with the differences being in what it was between the Blazer and the Jimmy trucks, and different striping for the camper and a different back door decal. Identical in the camper interior. Supposedly (I haven't found a confirmation of it yet) there were 1,780
total units made in the two-year run of these (that number is only seen in a 1979 Treasure Search magazine's statement, 2nd paragraph in our man
Dremu's old screengrab), and the GM factory confirms there were 1,555 of the Chevy versions. Do the math and you end up with 225 Casa Grandes.
The value of it as is now is a topic for debate. If it can be stipulated that the big dollar values in collector cars is in the ones coming closest to literal factory showroom-new dead nuts accurate restorations, this one misses by a tragic margin. Imagine if you found a tired but otherwise good condition Yenko Camaro, and chose to put in a generic JC Whitney carpet kit in a color not especially close to what the factory had, and then repainted in in a metallic copper that sorta looks like what a Yenko pastel orange might look like, and then painted the roof in a textured brown color while installing Pontiac Firebird inner door panels, and put on the wrong style emblems. It's what we have here, a never-used truck paint combo, the camper units were never painted like that, the truck's door panels are not factory-correct, and it appears to have the stainless steel/black trim that's seen on '76 model year trucks (I know the yellow-painted trim was a '77-only Chevy item, but I'll stand corrected if it was not also a '77-only GMC thing).
It may look all '70s style, and probably runs fine, but I'd put it at basic daily driver value for a 43 year old vehicle with nice new paint and carpet, probably half its asking price. The tragedy is that from the last I saw of it before it was repainted, the original factory pastel truck & camper colors might have been salvageable with a good oxidized paint removal/polish. Now, it would take mega-bucks of effort to peel off all that incorrect paint, if you want a factory-correct '77 collectible for investment purposes.