Looks like standard Dill Tower.
From the angle, it looks like the top has been modified, but probably just the angle.
Call American Tower in Ohio for info.
Or Dxengineering and ask for a rotor shelf that'll fit Dill Tower. Used to be a dude that made plates for Dill and sold them for $20 years ago.
I think Rohn 25 plates fit as well. Also easy to fab one yourself, if'n you got the skills.
Is this the type of rotor plate your were referring to?
American Tower Special Series Motor Mount Plate | eBay