Ok, I added the files for the Type VII skin I am using. I renamed these files for the 7c41:
NSS_Uboat7c_coning
NSS_Uboat7c_deck
NSS_Uboat7c_hull
I also copied a Turm file and renamed it for the Turm_6 & 7 decks.
I entered the museum and it appears to work. However, when I clicked to see the 1942 version of the 7c41, the conning tower was all rusty again. The prior version was skinned properly.
I also tried to use a skin for the IIB. I copied the DAT that I am using the IIA. I renamed the DAT itself, then opened it in a hex editor and changed the tga to a IIB. I then replaced the DAT in the IIB folder. When I try to load the Museum, I get a CTD. I reverted back to the stock DAT for the IIB. Isn't the IIB model the same as the IIA model? What did I do wrong this time?