Ball Joints on 4X4 - how involved?

[truckster]

OK, I know I could have posted this on the Blazer page or on the 4X4 page, but I figured more people hang out here so I might get a quicker response. I'm kind of in a hurry because I'm taking the boys to Scout camp next week and I wanted to take the Blazer.

I've got a 72 Blazer K5 I just got running. I took it to get inspected and emission tested and everything was good except the ball joints. They'll be happy to do them for around $500, but I can get the parts for $90. I have a 20 ton press and ball joints are nothing new to me, but the 4X4 is. So what do I need to do to get to the ball joints? The front axle is (I believe) a corporate 10 bolt, at least there's 10 bolts on the cover.

Thanks for your help.