John Deere 40 Series Block Numbers
(as interpreted by ToddT)


Please read the following information as to how this chart has been derived:

From day one, the Dubuque facility stamped the engines for each tractor model with a number. This number can be found on a flange on the engine block where the hydraulic pump and the generator are mounted. It may be covered by dirt and paint, but it should be there UNLESS the motor was replaced.

The Dubuque factory kept track in the production records of which engines went into which tractors. This is why it is possible to get a replacement tag for a Dubuque tractor even if you don't have the old tag.

I have assembled a chart to serve as a guideline between the various styles of JD 40's and the block numbers. I have used some of the following assumptions to generate this chart:

  1. I used the beginning and ending production dates as listed in J.R. Hobbs book, The Little Giants, page 30.

  2. I used the serial number breaks as listed in J.R. Hobbs book, The Little Giants, page 78. These serial breaks are listed for the production years, generally Aug 1 - July 31.

  3. I used the serial number breaks as listed in John Deere Tractors 1918-1987 by Deere & Company, pp. 61-62. This book indicates on page 60 that these are also supposed to be production year breaks. Quite frankly, however, I trust Mr. Hobbs' research more, and the serial breaks listed in this book seem to correspond closely to calendar breaks, as based on Mr. Hobbs' information.

  4. I assumed a 5-day work week, subtracting one day for Memorial Day, one for July 4, one for Labor Day, two for Thanksgiving, and roughly 5 days for Christmas/New Years.

  5. I averaged the production of each style based on the weeks the style was in production and how many should have been built by the time of the next "break", either the end of July or January 1.

  6. I have assumed that the block numbers started with 65001, only because I assume they would have started with some nice, round number, and because this seems to fit the closest to the other information I have. It is also relatively close to the starting serial numbers.

    June 7, 1999 - On receiving additional information, I have modified this to 66000.

  7. I have requested information from JD 40 owners in order to try and adjust this chart as needed. To date (Jan. 23, 2002) I have had 107 responses. These responses are enough to let me know my chart is close, but not yet exactly correct. Click here to see the responses I have received to date. Please, if you can send me information about your JD 40, we can work together to make this chart more accurate. (I need 40 style, serial number, and block number.)

  8. August 28, 1999

    I had some discussion regarding this with J. R. Hobbs at a local tractor show. He indicated that there isn't any correlation between the block and serial numbers because as the engines were built, they were "stacked" somewhere for use, and then were simply grabbed as needed. Yes, the numbers were recorded in the production registers, but there is no correlation. I believe there is some correlation, and I believe the responses I've received prove that out. If there truely was no correlation, it would not make any sense to proceed with this effort.

This chart still needs some work. I have not yet figured out how to accurately adjust it based on the information received from other owners.

This chart was created with the help of an Excel 97 workbook. If you are interested, you can download a copy of the workbook here. (JD40BLKS.ZIP 07Jun99 103K)

If you have any other information that can help me (and others) with this effort, please let me know about it or send it to me .

Thank you for your patience and understanding. Having waded through all this, go here to see the block number chart. Please note that this chart is about 40K in size and takes a minute to load.