John Deere Model 4520 Compact Utility Tractor Parts John Deere Model 4520 Compact Utility Tractor Parts - The 13-digit product identification number (serial number) is located on right-hand side of frame. 450 B Dash Wiring Layout Needed - starting issue Oct 15, 2012So, I am looking for the correct wiring diagram so I can discover where the loose wire should go and reattach it. I have a lead on where to buy a service manual on ebay. If it has a wiring diagram, I will probbaly get it. I was very happy to find the 450B to simply wired, and apparently easiy to work on, as that was one of my hopes when buying it. Model 40 Wiring Diagram Model 40 Wiring Diagram. This wiring diagram comes from Service Manual SM-2029, available from John Deere by calling 1-800-522-7448. The manual also contains other wiring diagrams along with additional information regarding servicing your magneto and other electrical components, as well as cross-reference charts showing the application of the various electrical components.