BB GM Heat Riser # 3940977

[John Brown]

Gary, the 3887024 valve on ebay is mainly for a small block. Look down further at the applications he shows from GM parts books. No doubt it's for a 2" exhaust system. The one I posted pictures of is a 2 1/2" valve for a big block. As I posted above, the 3746844 number on the weight is generic, same as the ebay seller says. It was used on both big block and small block valves.