It's been a while since I've scrapped a gas grill, but I'll take a guess. The top lid and bottom housing are cast aluminum and as far as I know are the only aluminum present. There should be about 16 to 20 pounds of cast aluminum.
I broke down around 10 Al grills this spring (I've still got the stack in my garage) and I don't remember seeing any brass valves. A few of them seemed to have some sort of zinc like valves but I never saw any that were yellow.
I just wish I would have cashed in a month ago when prices were higher :|
I used to scrap grills all the time. The aluminum top and bottom was really the only aluminum on there. I would also cut the brass valve off. Then just throw the rest away. Usually got 10 to 15 bucks for the aluminum when it was 50-55cents a pound...