it shouldnt be plastic... it's probably a cover your looking at. mine has a plastic cover over it.

the bk11 bypass kit came with a return line for the cap, no need for the $50 cap if you dont want to plunk down the bucks for it have a good look at the kit and it should be there.

 

The second gen valve covers are one piece. They are not like the 3rd gens that have a plastic cover on top. I still think the valve cover on the 2nd gens. is plastic.

 

it's aluminum. . .oh, and the kit comes with a return tap bolt. . .all you have to do is drill a pilot hole then screw it in. it is actualy designed for the oil pan and the thin sheet metal, but I can also see it working well for the top.

 

Yeah I too think it's aluminum, and that's the reason why I was a little worried about it cracking from vibration.. If it was steel, I'd feel a little better about it.