Got a 2003 H2 with now about 225000kms on it (had it for 14 years now). Anyone a few days ago I left for work and about 2kms up the road heard major grinding and what seemed like slipping or loss of power - as I slowed down it got worse and heard a clunk and the truck came to a stop. I tested to see if it went into reverse, which it did, so I drove it home in reverse even though I still heard a little clunking.

Anyway, this weekend I did some looking. I put it on blocks (all corners) and then put it in drive and kept it in 4HI Unlocked (the normal driving mode) and went underneith - I first turned the rear driveshaft (both ways) which turned no problem and the rear wheels turned fine - but the front driveshaft was not turning - should it have been turning too??? Next I tried to turn the front driveshaft and it would not turn (again, should it have with the H2 in drive in the usual driving mode)???? Next I started it and put it into 4LO Locked and got the wife to give it a little gas - the rear driveshaft (and rear wheels) turned fine, and now the front driveshaft turned fine but only the passenger front wheel turned at the same speed as the rears while the front driver wheel would turn at about half the speed and seems to speed up and then down like it was skipping (and I heard grinding noise in the front diff like a bad bearing or something). So next I drained the rear diff and got out about 2 litres - it looked OK - I refilled it with new hydraulic 75w90 gear oil. Next I drained the TC and got out about 1.5 litres which too was OK looking and then refilled with new Dexron III. I then went to drain the front diff and it was 100% dry (not even a drop came out) - I also noticed lots of dry fluid all over the housing. Based on the above, I assume it is obvious the front diff is bad - right? Does it sound like the TC is OK? As for the front diff, I started to remove it this weekend but couldn't get the drivers top bolt out due to limited clearance to grab the nut above the mount - will try again this weekend. But my other question - is the front diff unique to the H2, or can I use other GM front diffs out of say a Sierra, Denali, Suburban, etc???? I know I need a 4.10 gear diff, and have found some of these advertised from other GM trucks.

If the front diff is unique (no other model will work), would you guys suggest getting it rebuilt? I'm in Calgary, and here these are rare to find at wrecking yards and the few that have them want $1000+ for a used (non rebuilt) unit. I found a guy locally that rebuilds them, and he quoted me around $600 including parts and labour to rebuild mine.

Any advice would be appreciated.

Thanks