It sits between 1.4.3.5 (which added the crossover) and 1.4.4 (the “Labor of Love” update).
: GOG and Steam versions can generally play together via "Join via IP," but they must be on the exact same version number to connect. 4. Technical Requirements terraria 1.4.3.6 gog download
You can easily move the installation folder to a thumb drive and play on different machines. A Note on Modding If you are using tModLoader It sits between 1