We have a 1978 Prefabricated built in wood stove. There is no nameplate or serial # anywhere. I know the roof termination is a RLTSK8 / RLTSK8L. The side deflectors are metal and need replacement. Without a model # it appears no one can look measurements up. The inside dimensions of the fireplace are 35W x 24H x 19D. I think the deflector panels were approx. 15 X 22. Any idea what deflector panels can be used?