The required application form for a replacement (duplicate) title is available at the link https://media.dojmt.gov/wp-content/uploads/Application-for-Replacement-Certificate-of-Title.pdf Include a copy of your driver’s license.
By mail. Send the form and $10 to the Title and Registration Bureau, Motor Vehicle Division Headquarters, PO Box 201431, 302 N Roberts, Helena, MT 59620-1431.
In person. The Headquarters location and contact information can be seen at the link https://dojmt.gov/driving/#contact .
RELATED LINKS:
TITLE INSTRUCTIONS FOR SELLING A CAR IN MONTANA
REPLACEMENT TITLE – MONTANA
You cannot transfer ownership of your vehicle if you do not possess the Title Certificate. In Montana the registered owner of the vehicle is the one who maintains possession of the paper title.
REPLACEMENT. The title must be “replaced” if the original has been lost, damaged (rips, coffee stains, water damage), has cross outs or white outs, or has incorrect entries (such as seller’s printed name and signature not matching the official names on the front of the title) or signatures in the wrong place.