http://www.steelsoldiers.com/showth...ring-servicing-and-hub-replacement&highlight=
Start by reading the thread above, along with the TM sections quoted there.
As for replacing hubs... I think you mean disks-hubs... ie you can press the disc off the bearing hub... but I've never done it... luckily my discs on my m1009 were still within limits... on my 1987 R20 suburban they were not, so I just got the hub/disc assembly and reused my original bearings (they were nice and tight)...
Truth be told you won't know until you tear it all apart, measure the discs, and take a look at the clean used bearings to know what to do.
If you find you need new bearings, I always get the better warranty/good reputation items, and Timken have a good reputation... bearings failing at the wrong time can be catastrophic... or just a big pain in the but.
If you mean locking hubs when you say hubs... read my thread above.
