It was a 12LW like I think I and another pointed out in the thread where it was being sold. You're missing a lot of diff parts, unless there is some aftermarket diff I was unaware of. If you can't find what you need I can pull and old 12LW apart and show you what you need and in what order with a photo. But I probably won't have time for a couple days to do so
I'd say without a doubt your handling problems are diff related.