Mike,
I have replaced very few headlight switches in coaches, as in 1, because headlight switch failures are very rare due to the fact that very little current is actually routed through the switch, the switch only operates relays in most coaches.
There are several questions that need to be answered, like how did you determine the proper switch without the old switch to match everything to like the connector, mounting surface, and shaft? If you discarded the old switch (bad idea), the only suggestion that I can make is to either take the old shaft and new switch to the parts store and find a switch that fits the same electrical connector and the old shaft or buy a new shaft to fit the new switch.
Gerald