Funny how you talk about wanting more air flow. Back in the mid-80’s, we were cruising around in my buddy’s ‘66 C10 and we picked up a couple of girls that went to his high school. First of all, it was cool that all four of us easily fit across that seat and secondly, there was nobody “inconvenienced” thanks to the “three on the tree”. After cruising around town a bit, the girls started commenting on how cool that truck was because you could drive with both windows down and it didn’t mess their hair up. And we’re talking about the days of big Bon Jovi hair. I about fell out of the passenger side from laughter. My buddy was totally offended. “THAT?!!! THAT is why you think my truck is cool?!?!!!”
I don’t remember for sure. But, it would have either been LMC Trucks, Brothers Trucks, or Classic Parts of America. Those were my three suppliers at the time of that restoration. I’ve always liked having a sliding rear window for the flow of air through the cab with the windows down.