Hi Rick, welcome to Outdoorking. I've never heard of a Tecumseh engine on a Greenfield, but that doesn't prove anything. They mostly have Briggs and Stratton, but Honda is not unusual, and I think fairly recently some Kohler engines. However if they got the right offer from Tecumseh at some point, they might have taken it up for a short time.
The steering on ride-on mowers is usually not very wear-resistant, and they seldom get lubricated, so what you have ended up with is pretty common. Often some improvement can be made by rotating gears so they operate in unworn positions, and replacing tie-rod ends and simple linkages. Do-it-yourself enthusiasts often weld up the worn holes in various bits then re-drill them to the original sizes. It is similar to the process of rebuilding veteran cars, except that the design is usually even cruder on ride-ons.
The Anniversary 12-32 was manufactured in the late 1980s, and hence should not have included any Imperial fasteners except those that were part of American components such as the Tecumseh engine. However there is no telling what changes previous owners might have made, just by fishing around in a junk box to find pre-loved bolts.
Bear in mind that Greenfield still makes locally designed and made ride-ons. Their service department can tell you what new parts they can and can't supply for 25-year-old mowers.
Service information on the mowers tends to be contained in the owner manuals, along with illustrated parts lists. However while Outdoorking's manuals section contains quite a range of parts lists, there are very few complete owner manuals so things like belt replacement rely on posting detailed pictures of your specific machine, and hopefully getting some help from someone who has experience with that model or a similar one. Greenfield has had a large number of short-lived models, but some sections of the design have been fairly stable over time, while other sections have not.
