Why does my model number not exist?

Facts and knowledgebase about John Deere crawlers
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Recon-one
MC crawler
MC crawler
Posts: 5
Joined: Sat Jul 31, 2021 10:56 pm

Why does my model number not exist?

Post by Recon-one » Mon Aug 30, 2021 11:10 pm

I recently bought a JD 550 D. I went to the dealership in order to buy a new ignition key. The salesman asked the model number and I told him 550D. He said there was no such thing as that model. I asked why and he mumbled something about factory indecision and I did not understand. The number is factory stamped on the "vin" tag. He asked for the serial number and I told him that and he tossed me a key.
Can someone explain why that model number is real but is not recognized by factory records. The serial number is 268254 T.
The factory book that came with it said it is for a 1973 model, but that may not be correct, hard to say but it is old and has been used a lot.
I would like to learn about this dozer but first I think I need to know what it is.

Jim B
350 crawler
350 crawler
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Joined: Sun Nov 05, 2017 11:36 am
Location: western Maine

Re: Why does my model number not exist?

Post by Jim B » Tue Aug 31, 2021 4:03 am

Welcome to the Board.

Your 550 is not a D series, they didn't make a D. The ID numbering system JD uses can, and has, caused confusion before. In the case of your machine the D identifies the blade type, which is a 6410 blade. The model number followed by a blank space before the letter is for machine blade configuration (loaders were 555s). If the letter was shown tight to the 550 (like 550B) then the letter IDs a series of the 550 model. There would be a space after the B, then the blade configuration letter. Here are links to the 550 and 550B introduction sections from the on line parts catalogs so you can see the JD breakdowns of the "Product Identification Number" for the different series. JD's none current production 550 model series info shows they went 550, 550A, 550B, 550H. Serial number 268254 falls in the 1977 production run (261196 to 287203), so it is a 1977 machine. Hope this helps.
Jim

550 Introduction
550B introduction

Recon-one
MC crawler
MC crawler
Posts: 5
Joined: Sat Jul 31, 2021 10:56 pm

Re: Why does my model number not exist?

Post by Recon-one » Tue Aug 31, 2021 9:42 pm

Thank you, Jim
Just knowing the year helps in understanding the machine. I have repaired farm machinery and autos since I was small. My Dad wanted us to be independent so he had me tearing down engines before I was out of high school. In fact, just now I have torn down the final drive on my "inherited" International Harvester TD-340. It seems parts may not be available, that's why I bought the JD 550. On my farm a dozer is sometimes required. Getting back to the 550, it is a different animal in comparison to the IH dozer. I have always had a clutch to function, this is a "real" automatic transmission, even the steering mechanism. I hope the 550 holds up as good as the IH.
It has some things not quite right but by adjusting some valve levers I have already corrected some of the short comings. Your identification helps me know where to seek info when needed. Thank you again.

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