By the way, this reminds me...I follow this girl on Instagram with a 1972 F100, and she posts a lot of stuff from her late father's collection of car stuff. This past week she posted a bunch of pictures from a 1985 Montgomery Ward truck accessories catalog. I've never heard of this company, but some of you might remember it? Anyway, one of the pages shows a rear window tunnel accessory (Item M in the picture below, 2nd item down the right hand images). I can't read the details, but I assume it was meant for a similar purpose?
1994 F150 4x2 Flareside. 5.0 w/MAF, 4R70W, stock.
1984 F150 4X2 Flareside. Mild 302 w/ 5spd. Sold.
1980 F150 4X4 Flareside. 300i6 w/ 5spd. Sold in 2021.
1980 F100 4X2 Flareside. 351w/2bbl w/NP435. Sold in 1995