On a headliner truck the two offshoots on the end opposite the 'sharp' V will both have tabs for screws as both of the offshoots will go under trim.
Well, they should have tabs although the over the door tab doesn't survive well.
On a non-headliner truck the offshoot that goes over the door will be more rounded and will have an exposed screw hole in it. Seen from the back in photo 5 of this listing.
Here's another photo from my 80:
http://forum.garysgaragemahal.com/Headliner-A-pillar-trim-tp50710p50849.htmlThis is a good buy for someone looking as for some reason I have seen very, very few of the passenger side that doesn't have a crack at that visible screw hole.
Scott
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Camano' 1986 F250 Supercab XLT Lariat 460/C6
'Chanute' 1980 F350 C&C 400/NP 435 - Gin Pole
But there ain't nothin' wrong with the radio