(I'm not endorsing these sites, but they showed up on my Google search.) I'll give you $20.00, but if you spruce it up it could be worth a couple hundred dollars. Give an assist to Ron Wolfarth who is correct. It is known as a Traveler sprinkler. A heavy-duty model like this works quite well, actually.
It's the grownup version of the ubiquitous tractor sprinkler. It could water a football field in two passes, supplied by quick-coupler connections at mid-field. I think the impact head was a special high-trajectory model, for extra spray distance.
I’ve got one in my basement. Would never sell it. I put a 503 rocker jet head on top. Your model is missing its arms and I don’t know if you’ll be able to find a pair. Possibly contact Buckner directly.