how do I find out the year of JD crawler loader? I have serial number,

[beenthere]

Maybe this will help.
TractorData.com John Deere 42C tractor information

420C Serial Numbers:
1956: 80001
1957: 100001
1958: 125001
Final: 136795

I used to own one, but it had a custom built loader.. Fun tractor to use in the woods.. especially when the woods was thick with prickly ash that a person could not walk through.. But the crawler went right in, and a 360 degree turn mashed it down real good.

 

[Tx Jim]

According to SN it's a 1956 model.

 

[buickanddeere]

Better yet you can find out the day it was built , the day it was shipped , where it was shipped to and what it was optioned with.

 

[rodsauder]

OK, when I went and looked at id plate on machine it says its a model 420 c. So ,now from info you guys have given me I figure its a 1956 model. perfect. Thank You.