FCK,
We all remember how Uberti "enhanced" the Ladle to the '66. Went from one that was "bullet proof" to a new and improved brake-0-matic. What a groan.
The enhancements to the Breach Block/Firing Pin Extension were done for a safety improvement. The old type retaining pin for the extension rod left one with the face as the only thing to stop the rod in an OOB detonation. New one, much better. Now there is a
further improvement to lessen the problems of a broken (lots of those these days) cartridge support tab.
Depending on how old your rifle really is, you may only have a little rubbin-n-buffin to do to fit the "new" kit. One point, the business end of the firing pin still looks like the leading edge of a Bowling Ball and needs to be re-shaped. The firing Pin Return Spring is still to long and too stiff. Needs to be shorter and lighter. Cut it down and make it a mite lighter.
Coffinmaker