Kip,
Like T3 said there should be a number stamped on it somewhere. If not then grab your digital calipers. Measure the OD the ID and the width of the bearing itself. Grainger, msc and Mcmaster Carr should have what you need and a lot of these sites you can look a bearing up by it's measurements. Also whether or not it's sealed, ball or roller bearings. Also measure it in inch and metric because alot of companies use metric bearings. Good luck
Matt...