Notice: In case you enter key word "6303RMX" into eBay or Amazon, you will note the availability of o.e.m sizing bearings - 10X42X13. "6303RMX" is stamped on the OEM idler #two bearings. I've strong doubts about these becoming high quality bearings, including the Koyo bearings labeled as being designed in https://ukdirectoryof.com/listings13221339/the-smart-trick-of-collection-agency-in-anaheim-that-nobody-is-discussing