4x4 help
 

1998 GMC 1500
4.3L 5 Speed 4x4
30k miles with wide tires (might be important)

Okay so here is my issue. About a 2 months ago I noticed the flange on my front drive axle was wet (leak), but no fluid puddles. I checked the fluid in my front differential and it was good. I have checked the fluid twice since and it's still good so I assume its just a small leak out of the main seal? Thought I could put off that fix for a while, so I have.

Now that I laid that out, the last handful of times I have used 4x4 (on the floor), I'm having binding issues. It seems to bind (one large bang) once I get going, then subsides AND 4x4 works. I DID NOT DO THIS ON DRY SURFACES - snow, mud, etc...Well today we got 8" of snow so back in 4x4 the truck went. Same initial knock at start, then I got on the road. I could hear the 4x4 kick in when I was on the gas and out when I let off/coasted. I pulled over, kicked it in out of of 4x4 with some muscle to make sure the lever was back in 4 hi all the way. Got back on the road and had the same issue.

Any guesses on possible problems here? Obviously it is in the front differential or transfer case. I don't know if the leak in the front axle flange is coincidental (but my fluid level is good)??? I have the stock tranfer case and differential. I haven't touched the torsion bars. I've always heard that big/wide tires screw things up. I have 32x11.5x15 with a degree of offset. My truck is a reg cab short bed, so stock tires were 245x70x16. Any help would be appreciated.

the seal maybe going bad and also the noise when you put it into 4x4 is probably just the transfer case shifting i no in my older truck (88) it sometimes hase to be rocked to get it to shift maybe thats what its doin but check the fluids very good but your seal might be bad or going bad oriellys or napa should have that part