Mont. Code Ann. § 25-4-302

It is not necessary for a party to set forth in a pleading the items of an account alleged in the pleading, but the party shall deliver to the adverse party, within 5 days or additional time that the court may allow or may be agreed to by the parties, after a demand in writing, a copy of the account or be precluded from giving evidence of the account. The court or judge may order a further account when the one delivered is too general or is defective in any particular.