The K 181 is an 8-hp Kohler K-series engines. The only tractor that Cub Cadet built with that engine, and no starter/generator, with a regular starter, in a horizontal shaft engine, is the Cub Cadet 800, noted as one of the lowest production number Cub Cadet tractors ever at around 2350 only ever being produced between 1974 and 1976. The tractor was expensive for it's low-hp size, and Cub Cadet offered the 1100, which was a belt drive garden tractor with a Peerless rear differential, that cost less than the 800, but was 11 hp. therefore, the 800 was dropped from production in 1976, even though the rest of the quiteline tractors of that series were produced until 1979.
In 1979 when the red, *82 series tractors came out, the lowest HP garden tractor was the 482, with an 11-hp Briggs & Stratton engine.
The Cub Cadet model 86 had the same engine, but had a starter/generator. This tractor however, was the first Cub Cadet to come with the 181 - 8-hp engine. Previous models, going back to the CC Original, used the K 161, 7-hp engine.
So, if you've found one with the 181 engine and a regular starter, and it's yellow/white with blue stripes, then it's an 800. Having said that, the K-181 was a VERY popular engine, and could have been dropped into almost any CC model as a replacement engine, and MANY were sold as repower units for Originals, 70 71, 72, 73 tractors, which all had the 161 7-hp engine.