Estates of inheritance and for life are called estates of freehold; estates for years and estates embraced by the provisions of 70-15-202(4) are chattels real; and estates at will are chattel interests but are not liable as such to sale on execution.
Freehold Estates -- Chattels Real -- Chattel Interests
Mont. Code Ann. § 70-15-206, under Classification of Interests in Real Property.
Mont. Code Ann. § 70-15-206