All Classified forums require a Site Supporter subscription. It is only $25 per year and you can buy and sell whatever you like on the forum. To become a Site Supporter, go to Your Profile and select "Paid Subscriptions."
They are not a direct swap / bolt in, and they are not enough stronger than your 12 bolt to make it worth the work to use it. They are the same gears size, and center section as a semi floating 14 bolt that you will find in early 80 to 87 3/4 ton Chevy trucks.They are not sought after by anyone except as a replacement for what they have.