JD Part Numbers-What Does It All Mean?


One topic that I feel is very important to collectors is deciphering John Deere parts numbers, the topic of this month’s article. It was obvious from the people present at the workshop that many collectors do not really understand the John Deere parts number system. Given the complexity of the Deere numbering system, I think it is safe to say that perhaps no one can! But there truly is a method to the madness. I thought it might be helpful to collectors who are searching out parts for their restorations to get a better handle on what exactly a part number can offer in the way of information. That and the fact that I think I told Richard and Carol I would write this particular article about two years ago! There is actually far too much information contained in the part numbers to be completely covered in this article and much of it is not relevant or of crucial importance at this time in the hobby as it exists today. Let’s see if we can discard the nonessential parts and cover the basics of a John Deere part number.


First, although it is fair to say that all John Deere equipment is of at least general interest to collectors today, there are few of us who are actively involved in restoring equipment from the 1800s, at least at this point. We can then safely disregard the part numbers that encompassed the very old equipment that Deere manufactured. The hobby today mainly concerns itself with the tractors ranging from the two-cylinder era through the New Generation era, plus any associated and period equipment from that time. Major growth is occurring in the collecting of lawn and garden and snowmobiles also. Any part numbers from the two cylinders up through and including the New Generation tractors are thus fair game with a nod to the snowmobiles and lawn equipment. What follows is intended as a very basic overview of the part numbers and can be quite helpful in quickly identifying the era and application of parts as they are located. Much of this is what I have come up with after 20-plus years in the parts game and it has proven quite helpful to me and saved a lot of time. Take this information for what you can get from it and use it as you are able. I hope it is of benefit to some of you.


John Deere part numbers usually, but not always, consist of alpha­numeric characters. Remember, there are exceptions to nearly everything we will cover in this article. A part number begins with either one or two letters and these are followed by one to five numerical digits. There can also be letters at the end of the part number. An example would be AB1621R. This part number begins with the letters “AB,” followed by the numbers “1621” and ends with the letter “R.”


Of course, the letters and numbers vary completely from one part number to the next. Sound confusing? Well, it is and it isn’t. Understanding exactly what the letters stand for goes a long way toward clearing up the confusion. At first glance, it might appear that the part numbers are simply random pairings of characters, but this is not the case. Although I know the part number in the example above is for a radiator cap, I could still tell quite a bit about the part it refers to without knowing its exact description. The first two letters,” AB,” tell me that it is a part from the “A” and/ or “B” model tractors.


The four digits, 1621, tell me a little more. The earliest parts numbers were simply one digit, for example, D1R. AB1621R is a four-digit part number, so I know it is most likely a part number that originated sometime in mid-production and it is not from one of Deere’s earliest model tractors. By contrast, both D1R and 86R are from a very early model tractor, in this case an early “D.” 86R can even predate the model “D,” back to the Waterloo Boy itself! Finally, the “R” at the end lets us know that this is a part from the Waterloo factory. Since Waterloo builds tractors, then we know this is a part intended for a tractor and therefore of great interest to a collector.


A further insight is the fact that since the lead letters are “AB” and not “A” or “B” by itself, this is probably a part assembly of some kind. Traditionally, parts that are simple castings or gaskets or similar will have part numbers that begin with a single letter. Parts such as fuel lines or piston sets will nearly always begin with a two letter prefix. This does not sound as important as it really is but many times a part was listed by its two letter prefix while the main part in the assembly was only a single digit number. Intervening years and continual updates and revisions have often blurred exactly how remaining parts are identified today and so often a needed part has been relabeled with its single digit part number. So, although a search for a part assembly under its

original number comes back empty, perhaps it yet survives under a different number. This is certainly worth keeping in mind.


Now nearly all Deere part numbers follow this convention and for purposes of simplicity, it is best to use this system as a general guideline in identifying old parts. If we agree to follow this methodology, then it is a simple matter to list common prefixes and suffixes in somewhat of a quick reference form of general rules and tables. This greatly aids in identifying parts quickly. Perhaps the single most important rule to remember is that of the prefixes and suffixes. This alone allows the trained collector to ascertain what type of machine a part came from. There is some differentiation in the use of prefixes and suffixes but, for our purposes here, we can look at them together. As mentioned in the example above, the letter “R” signifies a part from the Waterloo, or tractor, factory. Other prefixes and suffixes are listed in the tables that accompany this article.


It is readily apparent that a single letter can allow us to at least make an educated guess as to what machine a particular part is for. A collector can then make better purchasing decisions armed with this knowledge. I cannot remember how many times I have been at an auction and noticed collectors swarming over piles of NOS parts that were clearly marked with a part number “AM–E.” These were mistakenly assumed to be for Dubuque built tractors, such as the model “M” or 40, when in reality, they were produced at the Ottumwa Works and probably fit a baler or similar hay machine. Obviously, there is a huge difference between paying a lot of money for a tractor part versus a hay machine part. In cases like this, if a collector paid a large price for a pile of parts like these, he would not be getting exactly what he had hoped for.


Another great benefit of growing familiar with John Deere part numbers is that it allows you to quickly verify if a part is even a Deere item at all. Remember, there IS more than one shade of green out there! If a part bears a part number that is roughly configured like the example, then it is safe to purchase it. Oliver and other companies use a different part number system.


Another feature becomes apparent. What do part numbers, as a rule, from a model “D” tractor start with? That’s right—a “D” or “AD.” What do part numbers from a model “A” start with? Again, an” A” or” AA.” The model “B”? Yes, a “B” or “AB.” How about a model “G” tractor? WRONG! As the story goes, Deere was originally going to name the model “G” the model “F,” but there was some concern over the distant but real similarity of the proposed model “F” being confused with the International “F” series of tractors. For this reason, the model was changed to the “G” but the part numbers retained the “F” and “AF.” And for some reason, part numbers beginning with “G” showed up on various hay rakes! Interesting, isn’t it?


We all know what model replaced the model “A”—the model 60, 620, and 630. They retained the “A” and” AA” prefixes on their part numbers. The same holds true for the 50, 520, and 530 having “B” and “AB” prefix part numbers and the 70, 720, and 730 having “F” and “AF” prefix part numbers. The 80, 820, and 830 tractors were all improvements upon the model “R” which had “R” and “AR” prefix part numbers. This held true through the later models.


Most collectors know that many grain drill parts begin with the letters “M” or “AM.” Now, these drills were built in the Horicon factory, which Deere purchased to add that line of equipment to its company. As history tells it, Deere was faced with closing the Horicon factory when the drill line was moved elsewhere. A decision was made to manufacture a line of lawn and garden equipment in the Horicon facilities and see if it could be made profitable. The rest is history. John Deere has gone on to enjoy great success with its line of small home owner equipment and it has grown until today it is arguably the single most important product line Deere produces. And guess what the part numbers for the new lawn and garden equipment started with? That’s right—”M” and “AM.” These were mistakenly assumed to be for Dubuque built tractors such as the model “M” or 40 when, in reality, they were produced at the Ottumwa Works and probably fit a baler of similar hay machine.


Also, since Deere strived to use parts that would fit on more than one model tractor, it is common to see parts from one model of tractor being used on another. This was simply Deere using an existing part instead of producing a new one. In fact, there are still a few two cylinder part numbers being used on today’s modern tractors!


There is very much more to the part number story than what I have just written about here. Vendor supplied parts, such as magneto parts, all carried their own type of number. But it should be clear by now that a little observation can yield enough information about a part number to enable a collector to make better informed purchases. A quick tractor oriented summary follows below. I hope these “rules” will spare someone from making a costly mistake. Until next month!

  1. If a part number ends in “R” or “T,” it is a two-cylinder (or possibly a New Generation) tractor part.
  2. Most two-cylinder part numbers will have either one, two, three or four digits in the number portion of their part number. An exception is the 20 and 30 series tractors, which had some five digits.
  3. “A/ AA” prefix part numbers fit the model “A” tractor and its successors, “A/ AB,” the 50 and so on.
  4. A part that is made up of more than one component part will have a part number that is different from the one cast into the individual part.
  5. The lower the number of digits in the part number, the earlier model it is from.
  6. In general, tractor parts tend to be more valuable than implement parts—for now!