Based on my examples, there is no correlation between early pebble production and lack of pebbles. All of the Proto LA that I have came with pebbles although I noted that the smaller the wrench the fewer pebbles I saw, which I guess makes some sense. My one Plomb/Proto transition wrench has pebbles. I have an earlier 1/2" drive ratchet that is more rough in the pebble area rather than having actual pebbles. My wrench with no pebbles at all is a chrome plated short DBE wrench which goes against the early tool = no pebbles theory. Here are some pictures. First are the Proto LA wrenches followed by Plomb examples.
-Don
I'm grateful for the photos. These are excellent and very instructive. And I would agree that these examples alone falsify the notion that earlier=no pebbling. Here's my read on them:
The last two photos of the end wrenches show both a no-pebbling and what I'm calling for the moment a heavy-pebbling varieties. Both bear the MFD mark, which makes them of a later minting than the MADE marking. The no-pebbling wrench seems to have a uniform patterning across the high areas of the beam as well as in the recess. I think this is a good 'control' wrench for comparison sake, at least for now.
Three of the ratchets have the MADE marking which is earlier. These appear to have what I've been calling the light-pebbling variety. While the 5449 is less distinct, the relief inside the recess has a much greater resemblance to the the two smaller ones in the photo, so from where I'm viewing it I'd still say it's a light-pebbling variety. It certainly doesn't resemble the no-pebbling end wrench in the last two photos. But the larger ratchet having the MFD mark has the heavy-pebbling.
If we were to formulate a premise just on these examples, we might say that:
--The light-pebbling is characteristic of the earliest pebble wrenches.
--The heavy pebbling is characteristic of the later MFD varieties.
This would still leave us with trying to place the later MFD marked wrenches with no-pebbling.
I still hold out the possibility that there may indeed be a chronology to the no-pebbling vs heavy-pebbling variety, but it would have to be contained within the MFD period.
In any event, I think your photos of just these few wrenches are enough to begin narrowing the possibilities.