Пробуй одну из:
ftp://64.243.178.145/nntpfile/root/_temp.files_/GRAPH%20APPS/MentalRay3_For_Maya___by__Titi2000/
ftp://ftp.tomica.ru/upload/MR3 for Maya/
http://66.197.131.31/upped%20by%20soulchild/mental.ray.v3.0.5.for.maya.4-trinity/
www.shockunion.com/stop-nbaaa/software/rayformaya4.rar