#30/74's tender tank (or at least the top half of it) is original from the Brooks factory. The C&S built an entirely new frame using the old tank. Other original parts on the locomotive include the driver centers, sand dome and steam dome rings along with the main and side rods, Many of the parts on the locomotive are marked both "30" and "74".
That said, Mike Trent is correct that the locomotive is C&S 74, it looks almost nothing like it did during its days on the Colorado & Northwestern and th eRio Grande Southern did little to change its appearance.
Jason Midyette