This is a Main Armature Bearing for a Lincoln SA-200. Fits most BLACKFACE welders and some Redface welders. There are two different bearings that were used and this is the smaller of the two. The Outside Diameter of this Bearing is approximately 3.15 inches (a little over 3 1/8 inches) or 80mm.
If your bearing is larger then check out this 6308 bearing (SA-200s machine codes 3417 through 5065 take the larger bearing).
This bearing fits the following machines:
SA-200, machine codes: 5107 and up.
Pipeliner 200 G & D, machine codes: all
Classic I, machine codes: all
Please call with questions 602-850-7399.