Snowblower model # question for ST/12

Does anyone know where I can determine what snowblower models will fit my Sears ST/12 tractror ? I'm looking at a snowblower model 842-260030 and the ST/12 model number is 917.25733. From what I've read it seems as though most of the attatchement are pretty universal among the ST models but I'd sure like to confirm it will fit before I purchase it.

Also, Does anyone have any thoughts on a 36" or 42" snow thrower for the ST/12 ? Would the 42" size be too large for the 12 horse Techumseh HH 120 engine ?