How do I install a past version of KSP to be used for modding without overwriting my current version saves?

[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.

[4x4cheesecake]

Right-click KSP in your Steam library, choose 'properties', switch to the 'Beta' tab and choose one of the versions shown in the dropdown menu. If the version you are looking for is not in the list, there is another (bit more complicated) way to get them. You may want to keep your other install, so choose a different install location, create a backup (at least of your savegame!) or rename your current install folder like 'Kerbal Space Program 1.4.4' or whatever version it is.

But I have to tell you some bad news: Savegames are not backward compatible! If you already load your savegame in 1.4.4., KSP will refuse to load it in an earlier version. You can still edit your savegame in a texteditor and change all version numbers inside to the particular version you want to play with, but there is no guaranty that this will work properly. (Maybe, if you have a quicksave which you haven't loaded in 1.4.4, you can try to rename it to 'persistent.sfs' but thats something I haven't tried by myself so I don't know if it is possible)

[Gargamel]

Also note, most mods are also not backwards compatible.  A 1.4.x version of a mod will usually not work in a 1.3.x install.   For that, you have to do a little digging: