I'm currently debating this. I have a NOS cup and cone BB (cup and cone and spindle came to me separately, but are all labeled shimano with no level listed, so probably lowest possible) that I picked up for ~$20. Never replaced a BB before and am not sure whether I should try using this, or just consider it sunk cost and go the easy route and get myself a UN-55 (that's the one where both cups are metal right?) or something.