How hard is it to replace a front-end differential?

What is your question?

I have called several shops who have given me estimates of 1200-1700 dollars to replace a front differential. I got my hands on a used differential and am toying with the idea of doing it myself. Has anyone done this, and can they give me information on things I may come upon while replacing my differential? Thank you very much in advance. The reason I am replacing it is because there has been metal shavings in the fluid for months now, and it has recently begun to grind, specifically when I turn corners. I do not want to run of the risk of doing anymore damage. When I replaced the hub assembly on both sides, I took the CV shafts out to inspect them, and they both appeared to be fine.