Some of the earlier 301's were fitted with the grease bearing. Later models and the 401 utilized the oil bearing. The bearing housing for both types looks very similar, the bearing casting has a grease-nipple tapped into the housing about mid-way along. So it is quite easy to tell the difference. The oil bearing housings will have a round, flat and unused projection in the casting that is not drilled or tapped as in the the earlier grease-nipple models.