GMC Horn Covers-For Squares?

[Ironhorse]

Recently acquired a group of parts and these were in a box. Pretty sure they are for square bodied GMCs but not really up on the square bodies being a
67-72 guy. The larger rectangular caps are grained vinyl with # 9761385 and # 157236 all marked "Inland" in a square box on back. The two smaller caps is a silver tone and the gold tone with the horn symbol on the other. Just the covers, no other horn parts. All are in VERY nice condition with good grain, two smaller caps have faint hair line marks. GMC lettering is really nice and bright. Appreciate any info for years and a value for them.