grinding noise while in 2WD

Hey everyone,
I'm a newbie to automotive kinds of things but I got a real problem. I have a 1991 S10 Blazer with a manual 4WD shift. When ever I drive my car there is a loud grinding noise comming from my front right wheel. I 've had my brakes replaced along with my axels , bearings, and ball joints. Nothing seemed to fix it. Everytime I got something changed the noise would go away and come back a day later. I noticed it doesn't make the noise when I shift into 4WD.

I've been surffin these threads for some problems like mine and found out something about a transfer case and a vacuum switch. I asked my mechanic about it and he told me it can't be a vacuum switch cause I don't have a vacuum pump.

I'd appreciate any insight anyone can give me.
Thanks,

Xeronine

If it is grinding constantly in 2WD, then the gear inside the front differential is chewing up and you will need to replace it. The cable that locks the front differential is likely binding and not releasing fully when you disengage 4WD. Drain the front diff fluid and if you have metal filings in it you know where your grinding is coming from.