I have a Grizzly G4002. Some time ago I did a modification to the steady rest to adapt cam followers as rollers. Cam followers are a better approach than ball bearings because they can handle a much higher load and are designed for this type of application. This mod also allows a 2" diameter shaft to fit. I don't know how similar the 4003 is to the 4002, but the approach may be similar. You can find a .pdf file as a post I did April 3, 2017 that describes the design. Hope this helps.