I understand that using any textures and the like from the original game of morrowind in oblivion is off-limits (as is the reverse). But what about using morroblivion specific textures and meshes in morrowind mods?
http://morroblivion.com/forum
http://morroblivion.com/forums/oblivion/morroblivion-mod-releases/4327
Read post 16 on this link Plus there are others through Morroblivion do a Search on you posting
You should ask permission to
You should ask permission to the authors of the mods. And other this I think that cold be a problem about the format, expecially the .nif that are copyrigthed. also consider that a converted mesh or texture can be low quality respect to create one from scratch