The transferee of a negotiable document of title has a specifically enforceable right to have its transferor supply any necessary endorsement, but the transfer becomes a negotiation only as of the time the endorsement is supplied.
Delivery Without Endorsement -- Right To Compel Endorsement
Mont. Code Ann. § 30-7-506, under Warehouse Receipts and Bills of Lading Negotiation and Transfer.
Mont. Code Ann. § 30-7-506