@ well I've been doing things a bit differently. Instead of replacing the head of the original model, I added it so both heads can be surfed on and off via skin files. It worked fine here: No errors or anything. Worked great. But now I'm trying to help @@Jolly and running into that issue. The difference with this one is, the head_0 and parts are named the same as the original model, so I tried renaming to a new name, head_b, which I renamed the objects, object data, and Ghoul2 properties to those names. So opening in ModView shows those and it looks fine. Just gives that error, and I can't figure out why. Error: Pressing okay and going through the Surfaces to find it all working fine: I also get this error with some certain models: Most of these questions are mostly directed at @@mrwonko.