The chuck on a Ryobi 1/2" drill press is stamped with RJ33-13L. The original
part is discontinued but some forum searches says that this chuck will work:

https://www.amazon.com/Ridgid-Ryobi-.../dp/B000P8MCYE

It looks like that chuck is stamped with JT33, which common and easy to find.

Is is safe to assume (uh-oh!) that any 1/2" JT33 chuck will fit the Ryobi
drill press?