You're right, but considering the level of questions that have been coming I thought it would be much easier for him to just replace the whole third member with something like this:
Mopar 8 3/4" (8.75) 489 Case Third Member or a used unit hence the price range variance which I gave.
Blunblu is right. In that you should determine if it is an A body or maybe a retrofitted B body diff or their in there to avoid a "why my wheels I wanted to use don't fit" post.
