Ditto what ATM said! Not only very precise work, but I've had it done by people who said they could do it, and screwed it up. Tried it myself once too, but gave up and just pulled it out and took it to a shop. Make sure you take it to a shop that only does rearends, not just any shop.
I also agree with ATM on the first response; just buy a good used posi rearend. Tons cheaper! Gears with cost you a couple hundred, and probably that much more for installation and setup. For under $400 you can get a complete 10 bolt posi.

 

once again guys thanks for the great advice

 

not good the closest one to me on craigs is 150 miles and is $1200, the hunt continues

 

I'd check every day and be patient! It may take a month of looking, but they come up occasionally.

 

That is what I do. I check morning and night. I use Craiglook.com though, I created an account, and you can save searches now, it will search a radius around your zipcode rather than changing to different towns in Craigslist. Much more streamlined.