They are pressed into the knuckles. Had mine done a couple years back and I got...well lets just say they didn't even buy me dinner first. The parts aren't really all the expensive as I recall. The Graveyard sells them for about $45 a pair. Might be able to find them cheaper locally. If you do it yourself invest in a ball joint separation and installation kit/tool. Although, the cost of the kit may exceed to total cost of the parts.