It all depends on the year of your truck, from 89 up the bearing was a once piece style, so you replace the entire collar and bearing. Earlier the bearings were a two piece press on style, I would recommend going to you local machine shop and having them press it on for you, it wont cost more than $10, if they charge you at all. Both bearings are interchangeable as they have the same stack height, simply different mounting. So, say you have the press on style bearing and no way of pressing it, you could essentially get the newer style bearing (one piece) and run it just the same. Hope this helps, Good Luck
Ends up, marlin crawler sent me the wrong one. They are sending me the correct one express for free!! So far these guys have excellent customer service.
I'm running Thier 160b clutch, I'll do a review on it once I get the truck running, hopefully by slamfest!!!