differences in 3 speed ball-change gearbox tops

[JonE]

I seem to remember commenting on a thread somewhere about flatting down the alloy casting on the underside of a conventional 3 speed ball change top to improve the ball joint fit by taking up slack.
I was cleaning up a "reverse pattern" top today and noticed that it seemed to be different, as there was a steel cup under where the ball would sit, above the screw-in alloy retainer. I'm now not sure whether the conventional pattern top was original, or missing a part, or... whether I'm getting confused with the earlier gate design.

Could anyone clarify whether the altered ball change top was improved in design for wear to surfaces as well as the swapping of gear positions? Or have they always had the steel cup below?

[Robert Foreman]

Jon,
         all the three speed ball change tops should have the perforated steel washer above the locking ring.

[JonE]

ok, thanks Robert - and so was there any other physical "improvement" through period of the two positional changes, or was it all otherwise identical?

[Mark R]

I think a gate change top would respond to removing a small amount from the bottom of the gate casting in order to remove the play, perhaps this would be what you'd seen. The later ball type tops I would presume all had a screw adjustment/fixing system which could be adjusted, presuming it hadn't been got at before by someone with hammer and chisel?