# Do Not Substitute 30320 or 30322 for a 30321 Cup-and-Cone

Adjacent 303-series part numbers are not field substitutes. 30321 is 105 × 225 × 53.5 mm. 30320 is 100 × 215 × 51.5 mm. 30322 steps up again. A cone that “almost” seats will run on the wrong raceway contact and fail early.

If the tag is missing, measure bore, cup OD, and assembled width, and also check cone width (49 mm) and cup width (41 mm) for 30321. Do not mix a 30321 cone with another cup.

The 30321 bearing listing isolates this size. TFL Bearing supplies a complete set; order cup and cone together unless your drawing clearly allows a separate cup replacement with the same series.