oiler hole ??? in Sprocket-Side Case Cover

I'll have to look for a part # but the "earlierest" covers used the smaller diameter 3 flute worm and a threaded cast aluminum clutch adjustment access cover.

Yes, I forgot about that threaded clutch adjuster cover. I'm betting the case cover with the threaded hole is part 256-15411-00. Superceded by the pop-in cover used on case cover part number 256-15411-01.
In the 70-71 parts manuals I have seen the following three numbers for the left-side case cover:
256-15411-00
256-15411-01
256-15411-09

Here's that very early 1970 threaded clutch adjustment cover hole...


It was on the cover with the very early spring anchor location that I showed in post # 40...


The same cover that I showed with the 256-15411 -1 part number casting in post # 40. So, that casting number was used on very early covers both with and without the threaded clutch adjuster hole, and with either of the two earliest spring anchor locations.


One last pic of the front of that cover.

Does that cover fit the 4 flute worm or the smaller three flute? The worm mounting holes are closer together on the three flute worm. Edit; oops got that backward, holes are further apart on the three flute.

All of the pics in my post # 43 came from an eBay listing, so I don't have that cover, and I don't have the worm. But, I compared it to the 256-15411 -1 cover that I do have, and I think you must have the mounting hole spacing backwards. I think the captions on the above comparison picture are correct.
I looked at this thread started by you:
http://www.xs650.com/threads/early-only-xs1-clutch-worm-gear-vendor.44169/
but you didn't show the outer worm.

You're no doubt right!