in the last week when i hit the 4-Hi button it engages 4-wheel drive, but it sounds like it is slipping on the passenger side, like with every wheel rotation there is metal on metal. it sounds like something isn't engaging fully. what should i check to start troubleshooting?

thanks for the help!

Most likely a problem with the clutch gear or clutch shaft, (parts 9 & 23). Here is an exploded view of the front axle assembly: http://img413.imageshack.us/my.php?image=frontdifferentialxw4.jpg