So I was playing with your mod (the most recent release) on Career Mode, and I couldn't unlock the Ranger engines... I went to the .cfg file and found that it said "TechRequired = experimentalAerodynamic" Well, the tech is called "Experimental Aerodynamics," so I added the "s" and made it "TechRequired = experimentalAerodynamics" in the .cfg file, and, sure enough, it he engine was there on next load. Anyway, I don't know if people already pointed this out, or if it's a bug or a problem specific to my copy, but I just thought I should make people aware! Cheers!