I don't believe it was ever a factory option. I know it was a dealer option for a while in the late 80's.
I put one in my '75 C10 I used to have. The deal with sunroofs is, noise and leakage. Leakage is harder to prevent than you think. The metal up there is very flexible and it's the cheap rubber gaskets on most aftermarket sunroofs don't seal very well. My '75 one I bought new and installed it, it lasted about 4 months before it started leaking, I ended up using siding caulk on it, didn't look pretty, but it didn't leak. Being a truck, you can't see the roof anyhow...
Factory sunroof options go thru alot of hurdles to prevent leaks and wind noise. I know, I was a body engineer (weld guns and weld spot engineering) for cadillac for a while right out of college. The caddies have a entire different reinforced roof panels, rain gutter inside the inner/outer roof panels, with drain tube running thru the body down the sail panel to the ground in addition to many other enhancments. So, next time you wonder why the factory wants $1100 for the sunroof option, you know why.