I had one made by Outfitter Truck Campers. I had the 8' Caribou model on a Chevy Silverado 1500. I'm pretty sure they make them for smaller trucks like the Ranger and Tacoma too.
The one that I had was very heavy. I think it was because the bottom and the top halves needed to be thicker plywood because they were open at the top and bottom. A solid wall can be made of thinner material.
I didn't think ALaskan made a camper that would fit a Ranger in the '70s? Regardless, the older Alaskan's were extremely heavy compared to the newer ones - somewhere in the neighborhood of 2200 LBs dry if I recall. That's more than double the weight of my old Four Wheel Pop Up and I ran it on a 1 ton truck.