Questions about my SM Deville

Hello guys, i recently purchased this beautiful SM deville on Ebay, overall i love it, but one thing i noticed is the back case is not signed. I'm just curious if that is normal for the SM deville? And is it possible if i could change the case for this piece? If i could where can i find the case for sale? I know the case is open from the top, which will make it difficult to open, do you guys have tips on to how to open it? Or should i just take it to omega store. Thanks in advance guys. Below are the pictures

Thanks alot for the response! If i want to change the caseback to a signed case, do you know where i could find one for this model? Thank you