The clad weighs 5.67g while the silver weighs 6.25g. Also the edges on clad coins show copper, the silver coins don't, they appear all silver
Here are a few from non-Mint Set years. These are quite a bit tougher to find nicely toned than those coins from 1947-1958, exclusive of 1950.
I hadn't even noticed that you previously wrote it was PL. D'OH! I had mentioned it might be PL because I have owned several 1946-S and 1947-S WQ with strong PL surfaces and one thing they have had in common is also very strong die polish lines similar to the obverse of your coin. They are very cool like that.