Wow. Interesting thread.
FWIW, I was one of the first to swap in manual hubs. I've gotten over 70K miles like that. Still the original bearings, and no failure.
The GVs came with "lock-out" hubs. Only reasons was so everything always spun, and the new "air diff" could do its thing any time, so they could market "Shift on the Fly", as all SUVs were doing it. This was Suzuki's attempt to make an existing platform do something it was never originally meant to do, and that is, run with it's hubs locked all the time.
To better answer Ian. This ended up making the axle housing seal on the pass side inner CV shaft prematurely wear. Techs would see this happen on Manual hubbed Kickers when the owners would lock the hubs and then drive 10's of thousands of miles.
Suzuki recognized this early on with the GVs. Not only was the seal "revised" several times in a matter of 3 years (can be seen thru the several "superceed" part numbers for that seal), but they even issued a TSB saying the premature seal failure was due to inadeguate filling of the front diff, and called for a WACKY fill proceedure of lifting the front end like 30* and then filling. This would over fill the diff and get oil to the seal (or they thought).
Apparently, it didn't work. Eventually, the seal superceed part numbers continued even after the TSB issue date. Leaking pass side diffs is something most Gv's are accustom to.
Now, that said, before I went with manual hubs, I too had a leaking seal right about 10k miles. Put in a newer sytle seal (has been redesigned since) and added the Warn hubs. After 70K+ more miles, it doesn't leak, and wheel bearing are good. Something to be said there.
I know of a few, some on this board, that do/did not have manual hubs and have replaced the seal many times.
Additional benefits:
- less wear on carrier bearings
- less rolling resistance
- ability to unlock hubs if a axle breaks
- fuggin' looks cool
I dunno if the last one really counts with most, but it does with me. It don't mean a thing if it aint got some bling.