Long story short, from a physical perspective, they all pretty much fit the same. I think it more comes down to what you want to interface with it. You can get a bellhousing for any of them (Ford, Chevy, Viper, etc.) I believe. The output yoke will vary from model to model, so you might have some funny u-joints depending on what you get. Internally the Viper ones are stronger as well, though most of that boils down to the input shaft as I understand it. I believe they all have the same shifter mounting location (where the shifter actually interfaces with the transmission shifting mechanism), but where the stick comes out varies from model to model. I'm not sure any of the factory ones work that well though. I bought an aftermarket one designed for a Ford that just has a two bolt stub shaft so I could mount whatever handle I wanted in case I needed to move it around.
