If it doesn't have the screw, chances are the spring and ball that go in there are missing as well I'm about 90% sure that the screw, spring and ball from the traxxas 2 speeds will work. I know they're mostly internal 2 speeds except for the 4tec, but I believe they will work.
100mph is easy (with batteries)
113mph nitro Racer2
115mph gas FG
107mph twin nitro buggy
99.61mph nitro buggy (ROSSA speed holder IC open wheel)