Thanks. I spent forever researching and calling the other day and my budget is slim so I went ahead and just got a proper geared open diff for cheap. Cheapest I found locking carrier was $250 + axle shafts and the places with the "locking" axle shafts didn't seem to know what they had. This is still a good project for what it gets you, I just have a third kid on the way and 4 cars. Working with the 3.5 9.5" axle like you did may be the way to go. More information on them.

Here are the part numbers for the axle shafts in 3.0 9" locking diffs.
mr377500
mr377501

It looks like the open/lsd axle shafts use MR377495 for both sides (if you have abs).