OK, I've finally confirmed from the previous owner that my older 229 with a 9mm conversion barrel was originally a 40 cal. I want to buy a new OEM barrel to return it to its original configuration. I see that there are differences in the 9mm versions of the 229 vs the 229-1 but I don't see any mention of differences in the 40/357 versions. None of the barrel descriptions from the various sources mention any difference. What do I need to know when buying a new 40 cal barrel for an older gun? Are they the same?

No difference exits for P229 40/357 barrels except the newer barrels have a nitride finish. The 9mm P229 is different in frame, locking block, barrel, & mags.

I was asking about your EFK on the for sale listing
I see you have a need for a 40 barrel OEM
I have one