Steam, as always, decides which version of a game you will get and the only choice after that is if you want to update to what they consider "current" (often delayed or missing latest versions).
This of course causes incompatibility with mods requiring a specific version of this (or any) game, say for example if a mod is no longer being maintained.
If you wanted to be in control of your computer, you should have bought the game elsewhere (like GamersGate) so you could install or change to whichever version you wanted to at any given time using regular standalone installers.
Sorry.
I see. Well thanks for the info . It's quite fun without a trainer, but just wanted to buff up some 'companions'.