Unknown Tow Hook Design ?

[Ironhorse]

My son brought these to me this morning and asked me about them since they look somewhat "similar" to the 69-72 style hooks on my '71 4x4. I've never seen these before at all. Seen a lot of tow hooks but never these. The ''hook" portion is the same but the mounting is totally differant. Has the number "379684 GM1" cast on the side. Both hooks are the same and hefty. Mount holes are 5/8" dia. and 3 3/4" center to center. Total length front to back is 10" and weight is just under 5 lbs. each. Would these be from a correct to our trucks era fire truck, school bus, big rig tow truck...??? Would make some awesome recovery hooks for serious off road use for sure. Mount to the front frame rail or rear frame member as the "hook" portion does drop from the mount section. Anyone ever seen these before?