Lionel had made the drivers available for separate sale when they messed up the J3 from 2001. They delivered the engine with disc wheels when they were catalog with boxpok. I had purchased a few sets. It took 25 minutes to change them out. The drivers are held on with a Philips screw. I'm sure if Lionel wanted to satisfy everybody, they would make the various drivers available for anybody that wanted a certain look.
Good to know.