Ok I found an a-body 8.75 rear axle with a 742 case not sure what gears but I was wondering what I would be safe paying for it and how much money I would have to put in it to make it a posi.
I've seen them up here in Michigan for 600 to a 1000 bucks for an open diff.
To convert to a SUREGRIP it all depends on whether you can find a complete center section or have to buy the parts and do it yourself. Prices will vary.
Too many people think they are worth gold. The fact is, the 8 1/4 is almost as strong and available more readily and cheaper. Don't get too caught up in having to have an 8 3/4. They are strong, but they aren't gold.