[HyperFX]

The drive pins, and ring gears seem to be the weakest parts I've found on my 410.
I stopped using the TD drive pins and use a solid pin with no flat spot, and two set screws for each pin. Shimming the diff so the ring gear fits a bit tighter against the bevel gear has helped prevent the ring gears from breaking teeth. Also, the screw holes in the front and rear bulkheads strip a little too easily, so I coat the stripped holes with epoxy, and cut new threads.
All in all, the 410 is more bulletproof than any other car I've owned for the last 24 years. All the others had many more "tricks" that had to be done, to improve durability and/or performance.