1984 Morgan 416 Chain Plate

[Dadidoc]

At the end of last season, I discovered a cracked aft main stay chainplate. I have since replaced it.
Cracked !

Now I removed both main uppers and they seem to look in good shape as seen
I did NOT see cracks in these other than one at end that looks like it happened during manufacture. Folks are trying to convince me that stainless has a half life - but I am reluctant to believe this. The shot peen process I think probably made them stronger than new ! Video

QUESTION: If I were to choose to replace any one pair, which to choose? the Uppers, Intermediates, lowers ? Which have the most load ? I am thinking the intermediates?

if anyone has time to peruse some of these pix - let me know if you see anything alarming!

thank you

Mike Barnes