How do you know if a 66 barracuda is a formula s or not?

737jetdr said
did all the 273 engines have adjustable rocker arms or just the commando? I know the Commando has a solid lifter camshaft.

They went to hydraulic cams in `68 and stopped using adjustable rockers at that time. You can find solid cams in the 2 barrel carbureted 273`s as well as the 4 barrel versions.