4WD still inoperable

okay i have a 97 gmc jimmy. my 4WD hasnt worked for about 2 years and i plan on gettin it fixed before it really snows here. i know its not the encoder or tccm. and i bought a new vacuum actuator and switch that goes on top of tcase. and when i push 4HI i hear everything click underneath the trcuk and everything but it doesnt engage. i realy think my problem is in the front axle. i read something about a clutch fork or sleeve or something. back when the 4WD stopped working, i think i wore down the splines on it because when i drove in 2HI you could hear something grinding in the front axel. so does anyone know which parts i would need to replace? i also found a picture but dont know what the parts are in it.http://i48.photobucket.com/albums/f236/JaVeRo/100_0120.jpg

well...anyone?

well...anyone?

Proper testing first.
Does the front drive shaft lock in in 4W?

Does the front axle locking in?
Does the actuator have good engine vacuum and does the cable pull all of the way.
Go threw this link for info.
http://www.automotiveforums.com/vbulletin/showthread.php?t=572914