As far as I know Montana quick attach was not proprietary it is the same as everyone else's or at least mine (2009 R4944) is. I have bought forks and a grapple and they fit like a glove, I used the neighbors attachments (Quick attach Kubota) and they fit fine. Your loader should have been made by amerequip
Design, Engineering and Manufacturing Solutions for OEMs, and Custom Equipment, Tractor Attachments and Backhoes - Amerequip (ARPS)
If you type in Montana Tractors in your search box it should come up as a parts and service company
Montana Tractors: Parts, Service and Warranty
go to contact us and there is a form you fill out and send in questions or a phone number to call. I just filled out the form over the summer looking for one of the handles for the quick attach received an email the next day. They had the part in stock gave me a price, I called gave him a credit card number and had the part in a day or two real easy. I have emailed them and talked with them several times not for parts really once I just wanted the paint code so I could get some mixed up, another I was just asking who made the loaders they have been real helpful each time. The only reason they shut down is because they irritated LS when they bought the farmtrec factory and they stopped selling tractors to them. I really haven't had any trouble with the Montana and I really like it, even had warranty work done at the end of the warranty period and I bought it new in 2010 so that warranty work was done just last March. Oh well I am just rambling now hope this info helps.