Hello from S California. Am restoring a John Deere 420 tractor. Which service manual is the most helpful, and where to buy? Thanks.
I&T is the only repair manual that I know of for "antique" tractors like that. There are probably books on restoring two cylinder John Deeres that may cover you. Those things are so simple that you can probably find all you need to know with a 30 second search if you run into something that isn't obvious. There are a couple of "competing" sites that are dedicated to old tractors.