levityler101

I'm rather new to the game and have played it for a few dozen hours. I have seen a bunch of very interesting mods I want to try. However, Most are not up to date with the current 1.4.4 version. How would I go about getting a past version of Kerbal Space Program to use those mods without overwriting my current playthroughs I've worked hard on? I have the Steam version of the game.