I am trying to upgrade my 12 bolt type O differential to a
mid 3 ratio gear...posi would be nice but I would settle for just
a better gear if I could find someone who has them new or used.

 

There's two members here that you should check with. Monzaz has new posi carriers for your housing and sells used parts, 507OLDS rebuilds rear ends and may have good used parts. The best way to contact them would be to send a PM (private message). You can read through their posts to see what they've had in the past. John