Not sure about the size of the needle bearing but i can give you the caterpillar part number: 91E4305100.
There is also a thrust bearing between the axle housing and steer knuckle that you may need to replace which is part number: 91E4300300.
Cat does not list any specs on the bearing sizes that i can find.
This is ONLY to be used to report flooding, spam, advertising and problematic (harassing, abusive or crude) posts.