Gravely 2 wheeler Technical Information
The basic Gravely tractor changed very little over course of production. The engines were the major changes, then the slow influx of modern safety features. Still, if you get the theory of operation of the first tractors, you pretty much have them all covered. Few manufactures' have produced a complex product for so long, with so little change. I guess when you get it right the first time, there's no good reason to change it much.
Manuals and parts lists for 2 wheel tractors
Installing an electronic ignition
Oil line routing for Canister and Spin-on filters. Bulletin 895, June 30, 1961*
* Courtesy of Bill Guthrie