GravelyManuals - OldGravelys: Gravely Manuals Westchester Manufactured 1964 through 1966. This was Gravely's first attempt at a riding tractor. 12 HP version of the Gravely Model L engine, but with an overhead valve head and cylinder designed for Gravely by Onan. OldGravelys: Gravely Manuals This site was begun in September 2003 by Chip Old. Sadly Chip died so I decided to mirror his site. I have left it pretty much as Chip designed it. Manuals · Customer Self-Service Jul 05, 2017Click Here to View Gravely Manuals . Manuals can be downloaded free of charge. Paper manuals can also be purchased. Please note, Service Manuals are not available for all models a service manual is not available for your model, the pertinent service information has been added to the Owner's Manual.