Ring gear bolt shoulders to large to go through ring gear flange on sure grip.

For everyone's information, I just spoke with Cass Eslick aka Dr. Diff who solved the mystery.

In 1969 Chrysler changed the bolt style and carriers to the shouldered size that comes in all the current kits, the 68 and older size bolts are no longer produced. The solution is to drill the holes larger in the 68 and earlier carriers.