This was with the '49 1 ton I just bought. Maybe someone knows what it is before I am able to get it open. The hinges are stuck, I'll use heat in morning.
It has 3 pieces. They are about 8" long. They unfold open to make something. One end is wider than the other. I can't tell what the writing on side is. The holder is blocking it.
My guess: wheel chocks (not likely) or warning reflectors?
I have a set of those. They didn't use very good plastic in the day, so some of them developed cracks in them. There is lots of plastic in there! It would be very hard to find one in great condition. It must have been a dealer thing or maybe CoOp or Western Auto because I have seen them in several of our larger trucks 4400 and up.
Got em open. They are Model 20, Miro Flare, Miro Flex made in Wichita, KS. They are in very good condition. Just need to polish the reflectors some. Here they are after hosing off.
Those are the correct Emergency Roadside Flares for your truck. They are pictured in the Dealer Accessory Catalog for both Chevy, & GMC. I have two sets of them. One NOS, & one used like yours.
Spanky Hardy Collector Of Fine Old G.M. COE Trucks & Antique Holmes Wreckers