If the original equipment bearing is scarce or unavailable, a digital caliper and a progressive size chart from any of the bearing supply places might come in handy if you've got the failed bearing to measure. Timken, BCA, etc. all have standardized bearings that will work in a variety of applications. Sometimes the only difference in an industrial-application bearing and an automotive one is the part number.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!