The ones I've seen look like Sinclair SD110 series folded dipoles.
Same type used by CalTrans on their low band system.
I have observed both of those antenna types, or something quite similar on different CHP towers. I think Fresno had the omni and Merced had the folded dipole. I could be confusing the locations though.
Do you recall how much of six it covers, or is it narrow?
Someone loaned me a Cushcraft 6m vertical. I took it down and the guy doesn’t want it back. I forgot the spread on it.