I currently use 0.38.67, so I am not sure about compatibility with anything lower. However, I have decided to upgrade to 0.4.5.1 as it seems to be far superior in every way, from graphics to performance. Everything will be compatible with .38 and up, but they *might* work with .37. It's all completely standalone as everything (except the drivers and tires) were made from scratch, but even those were heavily edited. I made everything for .38 so I still need to convert the tracks to .45. Thanks, I built various prototypes but scratched them at the last minute when I thought of this design, I'm not sure if I even have the others. This one in particular is supposed to be a solar-powered purpose-built MT stadium in the desert.