A few years ago I ~completely~ rebuilt my JD 853A row head...I mean everything but the sheet metal!

I got it all from Shoup, and was very happy.  I was a bit leary of their gathering chains for some reason, but when I got them, they looked identical to JD's, and cost a lot less.

I have used Shoup for a lot of other stuff, but you probably know that to completely rebuild a row head is a good little chunk of change..I continue to be impressed by them.