Actually there's even more. There's Blackhawks and Super Blackhawks. there's Vaqueros, Bisley Vaqueros and New Vaqueros. There's Blackhawk Flat Tops, Single Sixes, Super Single Sixes, Bisleys, Bearcats and Old Army models.
The Bearcat is a very small framed .22lr model.
The Single Sixes are small framed and have been available in .32 mag and .22lr/.22 mag models. The Super Single Sixes are built on the same frame but have adjustable rear sights.
The Blackhawk and Super Blackhawks are built on large frames - both use the same frame. Typically the Super Blackhawk is chambered in .44 magnum although some Hunter models were made in .41 magnum and .45 Colt. he Hunter models have the integral scope mounts on a bbl rib. The SBH is also available with an unfluted cylinder on some variations. All have adjustable sights.
Vaqueros are basically a Blackhawk frame but with fixed sights like those on a Colt SAA. Bisley Vaqueros are simply a Vaquero with a bisley gripframe, hammer and trigger. New Vaqueros debuted this year and are built on a smaller proportioned frame yet still have the same sights - fixed. They're only available in .357 and .45 Colt. They're closer to the size/weight of the Colt SAA than the larger Vaquero is. the larger vaquero was available in .357, .44-40, .44 magnum and .45 Colt. Some were also made in smaller runs in .32mag/.32-20, .38-40, .40 S&W and 10mm. Some Single Sixes are also a scaled down model Vaquero. The current offering of .32 caliber ones are as such. These are the only models available in either blue/color case finish or in a high gloss stainless.
The Bisley models are simply Blackhawks (Super BH in .44) with the Bisley grip frame, hammer and trigger. The .22 Bisley is on the small framed Super Single Six frame.
The Flat tops are new this year also. They're built on a medium sized frame like the "old model" Blackhawks were but with the transfer bar system. Currently only available in the 50th Ann model, a large frame Flat Top Blackhawk in .44 magnum is to be made in '06 to commemorate the .44 magnum cartridge. The medium sized Blackhawk Flat Tops are to continue production in non-commemorative models.
Grip frames...whoa, there's the one on Blackhawks, Vaqueros and Super Single Sixes. They're aluminum. A short version of this one is on the .32 Single Sixes. The SBH's have a slightly longer one. Some SBH's have rounded trigger garurds while others will have the square backed dragoon style. The SBH gripframes are steel rather than aluminum. The Bisley models have a longer more vertical grip which most agree is nicer for comfort especially with hevier loads. Allows better roll in the hand. There's also the birdshead style that was available on some fixed sight models. Most will be the cocobolo wood. Some have been or still are available with black mircata or white mircata. Hunter models have black laminate grip panels. Flat Top models have a hard rubber grip panels as do the New Vaqueros.
The old Army is the blackpowder SA that Ruger offers. Kinda a Remington 1875 mixed with a Blackhawk. It's a whole other animal.
Phew... Ok so for a Stainless, fix sighted, .357 with a short bbl, you'd likely be looking for either one of the older Vaqueros or one of the New Vaquero models. Both availbel in a 4 5/8" bbl. A small run of sheriff models with 3 1/2" bbls was made also and may be able to find one after some hard looking.