Forgive my pompousness if this tidbit is already known but I googled and didn't find it. CaptainFwiffo's posts about identifying 1921, 1922, and 1924 dateless buffs were very helpful and hopefully this will be too.
While sorting our vast pile of well-worn and often dateless buffaloes I noticed that some had very close-together ribbons. Then I found a readable date 1925 and it had the same close ribbons. I set aside all of the close ribbon dateless buffs for further study. It does appear that only the 1925 buffs have this easy-to-identify ribbon morphology.
This morning I selected three of the dateless close ribbons, photographed them, and then acid-treated the dates. All three of the test group proved to be 1925.
While this is not an earth-shattering tidbit, being able to identify with certainty a dateless buff without resorting to acid is nice and I hope you find this information useful (and I hope it is not just a rehashing of a long-known clue)

Below is a picture of the salient features of the 1925 ribbons. Notice how close they are. Also, the recess between the ribbons may be a bit deeper than other dates because it often extends further (longer) than in other worn dateless buffalos. The ribbons remain parallel at the shoulder, taking a slight turn to the right.

The closeness of the ribbons is not subtle when compared to other dates. Here's a sampling of other dates and the 1925. Also notice how the ribbons diverge at the shoulder in other years:

And lastly, here are my three test coins:


