Which master cylinder has the screw-on caps?

Much to our dismay, the lid on Aaron's M/C has been slowly leaking fluid down onto the firewall and has eaten some of the paint off. I got a new flashy chrome one and it leaks some too.

So, is there one of those newer master cylinders with the screw-on lid, rather than the lift-off lid held with the wire bail, that is a direct bolt-on for his Dart Sport (manual front disk - rear drum)? Any modifications necessary?

One other thing... the brake light stays on constantly. I'm guessing it's a problem with the proportioning valve. I know the emergency brake switch is OK.

Jerry