They definitely made them, just not very common at all.
You can get them if you hunt a million bone yards - stripper model work/fleet trucks are your best bet - or through LMC for megabux. They refer to it as "green tint" but that means green kinda like an old Coke bottle, similar to the other "clear" glass in your truck. You also might try some of the other parts dealers like Classic Parts.
I had them on a '95 3/4 ton parts truck a while back. Only one with clear extended cab windows I'd ever seen -
Except for an '88 that had the fixed (non-opening) windows, another parts truck of mine -