Welcome to TBN!
First off, no need to post the same thing twice, but when you do post, please be more complete in your question.
The elbow and grommet on the top of the fuel tank on the JD 4500 is a return line, so there is no pickup tube. The grommet and elbow are available from John Deere. The line is regular fuel line, probably 3/16" from an auto parts store if you need that.