Raven Rock Mountain Complex (RRMC) has a requirement to purchase of Caterpillar Inc. repair parts that must be Original Equipment Manufacturer (OEM) Parts for warranty issues and longevity. ALL or NON... Raven Rock Mountain Complex (RRMC) has a requirement to purchase of Caterpillar Inc. repair parts that must be Original Equipment Manufacturer (OEM) Parts for warranty issues and longevity. ALL or NONE.