Guidance as to what series of tractor

Where do the series letters come from? The answer needs to be in an FAQ or sticky for us newbies. I have two old Sears tractors. One, with a 10hp Tecumseh HH-100, is P?N 917.99410. The other, with a 12hp Tecumseh OH-140, is P?N 917.99421.

BTW, who was 917 (the supplier of the tracotr to Sears)?

This website focuses on the two prevalent models of what were called Garden Tractors in their day: the Suburban Series and Custom Series. Throughout the model years they were referred to by different nomenclature. In the beginning years it was just the model and three digit numbers which typically referred to horsepower: Suburban 725, or Custom 600.

Later there were Suburban 10's, and 12's, again the number being the horsepower. Same with the Customs: Custom 10 and Custom 7. There were SS-12 models, which were supposed to be just a little more "pimped out", than the common Suburbans. And there was an oddball thrown in here and there, e.g. Custom 10E. The "E" being electric start I assume. Then there were the “Sears Best” Hydro-Tracs. They were Suburbans with a hydrostatic transmission.

When the Onan twin engines were added to the line, the single cylinder Suburban's were given the letter designation of ST. The oddball of course was the ST10, which actually was based on a Custom frame, but carried the ST designation. In the mid/late 70's, all naming bets were off, as the traditional Custom line was diluted with tractors made by Murray. The frames got lighter and vertical shaft engines were used. There were some interesting tractors from this era, but they are generally more difficult to find in good shape than the older machines.

The Suburban style tractor was made until the late 70's. Although not called a Suburban, it was still the same basic construction. The sheet metal may have been lighter here or there, but it was still recognized as a Suburban. These tractors were referred to as "Twin" in their model name for some years. As the sun set on the series, they were called GT for garden tractor.

Roper made most of the tractors that are represented on these pages. As mentioned above, in later years some of the "entry" models were made by Murray..

Thanks for the answer. Spence, but I still am not sure if my tractors fit here, since I don't think the owner's manuals mention "Custom" or "Suburban." If I could post photos I'd do so, but I'm fairly new to computers.

Both of your tractors are Suburbans. If you go to the Sears Parts Direct site and put your model number in, you will see the parts breakdown for the tractors.

www.partsdirect.com

The mystery to me is why that 66 Suburban has a later model engine. The overhead valve motors were't used until several years after your tractors were made. They are usually taller than the valve in head motors, and the hood usually needs to be raised to fit the valve box.

Go to the tractor identification area of this site and look at the Suburban models. You may recognize your tractors there.