I have an 86' sport coupe, I know the rear doesnt have posi, and I obviously want to have posi....thing is, my rear is in great shape, so I dont want to buy another used rear from ebay, and do it that way...but new posi units are really expensive as well.

So I browsed some auctions and came up with this

would this be all that I needed to install posi? Im not so sure if it fits or not either, but any help would be greatly appreciated. Thanks in advance