IDing a Browning T-Bolt replacement stock

Does anyone know how to identify a factory replaced stock? I just got a 1967 Belgian left hand T1 that may have been a salt wood gun that has had the stock replaced. It has a very small spot of bluing gone but no active rusting on the barrel just ahead of the receiver. The stock is not the oil finish that my 1965 right hand T-1 has and the bottom metal is a matte black whereas the earlier one is bright black. The finish on the stock is perfect but appears to be a satin poly type. The wood screws are like new. There are several markings stamped inside the inletting and am wondering if any of these may represent a factory replaced stock.