This is a Main Armature Bearing for a Lincoln SA-200. Fits most BLACKFACE welders and some Red Face welders. There are two different bearings that were used and this is the smaller of the two.
The Outstide Diameter of this Bearing is approximately 3.15 inches (a little over 3 1/8 inches).
If your bearing is larger then check out the 6308 bearings.
Please call with questions 602-850-7399.