I know this is an old thread but I came across it today while searching for something else. I wanted to pass on this information for what it's worth. I have multiple Western Specials and one Rice Special along with other Standard 55/555's.
Through my research, my understanding was that the Western and Rice models were basically the same short of the R-2 Rice tread tires on the Rice version. The printed promotional documents support that the main differences from a Standard 55/555 and a Western/Rice version is the 18-26(23.1x26) rear rubber, high arch front axle, the rear step plate, and if a diesel model, it would have the Bosch APE inline injector pump instead of the regular Bosch PSB pump. I would also tend to agree that the Hillside was an early version of the Western and that the name was changed to Western on later versions.
From what I can tell from my tractors, they did not call out the W on the early tractors even though they have the 18-26 rubber, the high arch front axle and the Western style rear floor board or step.
Then to really throw a wrench in the mix, I have a 1950 55 Riceland Special, model number 55 GSH, serial number 1106. This is a gas, hand clutch tractor. It does have the 18-26 R-2 Rice tread rear rubber and a high arch front axle even though the model number does not call out the W for Wide axle. The tractor came out of Alvin, TX not far from the gulf. True rice country.
The real oddity on my Riceland Special is the fact it does not have brakes of any kind and never has had. I know everyone will call BS but it was how the tractor was built. There are no pedals, brake pedal cross shaft, brake housings or brake pinions. Simply block off plates on the rear differential housing similar to those on tractors with no PTO. No pedal wear marks on the floor boards either. I will attach pictures of the right floor board and also the brake pinion block off plates.
I have spoken with a gentleman in Pascagoula, MS that farmed rice. He claimed that Case made many 500 and 600 model Rice tractors the same way, with no brakes due to the fact that those standard tread tractors had brake housings that were mounted very low on the rear differential housing and in the mud and water, the brakes would freeze up so the manufacturer eliminated them to keep rust and water in the rear differential from being a problem.
I hope this helps outline what the Rice Specials were.
Thanks, JMB