Mark, great observation on the 4 round areas of the backing plate ! Make me (almost) want to remove the rear wheel on 232 and see what's in there ! It's really great you have the later vins to compare parts to ! 4363 came first to me, what was there appeared original to bike, by the time i had 232, 4363 was restored, so nothing to compare to. 2157 came after 232 was restored, so again, nothing to compare these finer details to...
The one distinction of 232's rear sprocket carrier, which i believe we've discussed in other posts, was the 4 bolts fixing sprocket to carrier, these bolts had early "8" on the face of the head.
I'm so glad you are able to take the time to compare parts. Being anal is what restorers like us do; it's careful observation to documenting what we believe correct for a particular vin production run.
Would say the details on the inside of the backing plate on 97 should go on the distinctions list.... ?
Seems it's easy to lose these distinction in posts which, in some cases, tend to get buried in the BB..
If you guys think of it and have the time, would you shoot me an email, that way i will be sure to get them in the "Distinctions" list.