I've found an even easier way to do a straight swap of model parts. To make it easier to understand i'm going to call them the donee ( The model you want to add the new part to) and the doner ( the model you are taking the part from to add to the donee) First extract to open formats both the models into a new folder (just makes it easier) Next open the donees folder with all the different parts in and make a note of what the parts you want to replace are called (lowr_000_u_high - lowr_000_u_med). Next go to the doners folder and find the files you want use and rename them exactly the same as ones from the donee then simply copy and paste them into the donees folder ( Sometimes they are only named one letter different so make sure they are the same) Then launch OpenIV go into edit mode import the ODD file and if you have done it right it should have swapped the model parts over. I found this method alot quicker and easier then editing the text files. (Remember to make backups just incase)