Mont. Code Ann. § 61-3-421

A resident of this state who holds an unrevoked and unexpired official amateur radio station license and operator's license, "conditional" or higher class, issued by the federal communications commission of the United States, upon proof of ownership of the amateur radio station license and operator's license, may be issued a set of license plates displaying the official amateur radio call letters of the owner as assigned to the owner by the federal communications commission for a light vehicle or motor home owned by and registered to the resident. The plates must be renewed as provided in 61-3-312.