Help identifying roman tub faucet and how to remove handles

[Cpseudo13]

Anyone know the Mfr. of this roman tub faucet and how to remove the knobs? I believe it's original to the house which was built in the 70's. The tub spout has a set screw at the base so I got that figured out. I've tried unscrewing the knobs, I even tried unscrewing and/or popping the stepped part off at the top thinking it might have been some sort of cap or something. Best I can tell, it's not. So I'm hoping someone here can help me out. Thanks

 

[Breplum]

If there is no cap to unscrew, then possibly they are push-on handles though I've never seen large knobs pop on to nylon stem heads the way Grohe did in the 70s