Whats JD reasoning for the lettering system on A's

The "D" was a success but the "GP" was not, so in 1934, Deere replaced the :GP: with two tractors, calling the larger one "A" and the smaller one "B".

The letter "E" had been used for small stationary engines, and the letter "F" belonged to FARMALL (as in the "F-20") so when the larger than an "A" tractpr came along, rather than use "F", Deere chose to call their new tractor "G".

"H" became the next Waterloo design released, the letter "I" was used already to indicate INDUSTRIAL. Why "J" and "K" were not used is a mystery, but "L" became a small garden tractor, "M" became Dubuque factory's small utility tractor, "N" was a Waterloo Boy model and also was used as a suffix letter indicating NARROW,

"O" is an ORCHARD tractor, "P" indicated POTATO Tractor during the "GP" production, "Q" was not used, "R" became the big diesel, "S" means STANDARD and was a suffix, likewis "T" which means "TRICYCLE" and "U" which means utility. "V" was for vegetable, "W" was a small row crop utility.

If in 1918, John Deere had been able to foresee their entire line of tractors through 1952, they might have developed a coherent and sequential series of model designators like they did starting with the 40,50,60,70 snd 80, but when they were developing the "D" all they had was one model.

I would add a few of addenda:

The "D" was indeed the fourth iteration of the "bathtub" design Waterloo Boy" that was in development before JD bought that company. The photo is of a Waterloo Boy Model "A".

It's been been oft repeated in several books that early telephone ordering resulted in confusion between ordering a "D" or a "C", and that was why they changed the designation. Also, they felt it would expand on the notion that with its high-arched front axle that the "GP truly was a "General Purpose" aka row-crop design, capable of taking on the chore of cultivating.

The "A" came out two years before the "B" and proved so popular that smaller farmers wanted an "A" type tractor in the 1 to 2 plow class. So, the "B" came out and was advertised as 2/3 of an "A" in power and price.

Originally the "G" was going to be the model "F", and if you look at casting numbers on a "G", or a 70/720/730, you'll see for the most part they start with "F" and not "G". After marketing thought about it and considered that IHC's line of General Purpose tractors were all prefaced with "F", Deere skipped that letter so to avoid confusion and not risk being accused of stealing a model number out of jealously.

Our old dealer who has been in business carrying Deere since the late 1800's once told my dad as he waited while my Grandad arranged delivery of his new '40 "H" that the model letter stood for HORSE as it was intended to replace a team and Deere thought that that model would be just the right price and size to do that. In fact, Grandad sold his last team soon after they reconfigured the planter hitch. Not sure that this story is true, but it does fit the times and purpose of the model.

When the 50/60/and 70 were usherd in around '53, Deere marketting thought about calling the new line the "Super" series ("Super A, Super B, Super G"), but again, not wanting to mimick IHC (Or Oliver), the early numbered series was begun instead.

When the -30 series was on paper, and into early development, those models were going to be called -50's (in fact there are quite a few photos of a prototype tractor bearing 750 decals floating around some magazine pages).

Then how they decided to come up with the new generation -10 series is interesting as well. But you have to remember that it really began with the 8010! ;)

Frank

420, 830, 7020, are a few examples.