I'm looking into replacing my center differential soon on my 2000 outback limited 5 speed. I want to replace all the bearings in that section too while I have it apart. My question is when I look online at the parts microfiche for the bearings I get two part numbers. Next to the numbers it says for m/#449123 or m/#449124. I can't figure out what those numbers mean. Only difference in the bearings are a thickness of 1mm and twice the price. I'd hate to order the wrong ones. Hoping someone can help me with these numbers.