That is a very nice car, so congratulations. That brass tag looks like an inventory control number. I worked in the auto industry in the 1970's. Brass tags like that were attached to everything that was considered an important asset of the company from metal desks, cabinets, machines in plants, company cars, etc. Once a year each building needed to do a "bras tag count" to make sure it agreed with the inventory sheet. Our tags were oval, about 2" long and had more digits. More like room for five numbers. So if the back side has some sort of attaching mechanism, that is what I think it is. So it could be that this car was owned by Trico and was in their company car inventory.