The #15 was a one-row mounted picker, basically 1/2 of the Model 25. I do not know what improvements were made to become a Model 25A, but the pictured picker with the gauge wheels (carrying wheels) is a 25 or 25A, the 226 was the next series of JD 2 row mounted picker. (I do not know if the 226 was ever made into a one-row, but the one row mounted pickers resumed, and ended, with the 127.
Has anyone ever seen a photo of a #26 JD corn picker? This was an experimental version that Deere was working on very similar to the 226. When I have more time, I will post the photos of it that I have.
I also found information on a 226-G Corn picker - Deere made a conversion kit to mount the 226 picker on styled GM and G tractors - more on that one later when I get a chance to post photos.
Here are photos of a #26 corn picker - the difference I see in the photos is this picker did not fold in the middle like the 226 did.
There is a good photo of the #26 in the book John Deere Model B Photo Archive on page 129 - it's a Deere studio photograph from 1939 showing a 26 picker. I see a lot of differences in it vs a 226. I will try to scan in that photo and post it someday.
The 226G picker I mentioned earlier was aSupplement to an Operators Manual (OM-N2-548) for the No.226Gcorn picker which described the special parts and procedures for mounting a No. 226 corn picker on a Model G tractor.
For the No. 226G corn picker, special equipment was designed to mount the basic No. 226 corn picker on the Model G. This special equipment included the drives for the picker, husking box, husk auger, husking rolls, power shafts, wagon elevator support, transport axle with wheels, raising pipe and tilting lever, muffler shield, and radiator screen and engine shields. The radiator screen was 2 pieces of fine screen with reinforced edges that was attached over the existing grille screens and tied in place with short pieces of wire. The radiator screen for the Model G was unique as all other tractors used a separate radiator screen to replace the tractor grille screen.
I will try to scan some of that manual and post when I get time.
