I recently ordered a new switch from The Bonneville Shop. They listed both the early and late parts. I ordered 60-2133.
What I got was LF Harris, and has a straight thread and an O ring in place of the usual copper washer.
Intriguing ... 60-2133 is the earlier of the two numbers the trade's used (60-3719's the other); the later number must be NPS; if 60-2133's also being supplied as NPS, what's being used for NPT?