Identifying Switches (Model M)

[Yossarian22]

I have three Model M keyboards.
You guys here seem to be connoisseurs. How do you know what switches get used in the keyboard?

By date? Serial? Manufacturer (it is my understanding a lot of Model Ms were made for IBM by Lexmark)?

 

[Radical]

Look here: http://geekhack.org/showwiki.php?title=IBM+Wiki

 

[Serpico]

Buckling spring switches

 

[Pylon]

There's a few rubber dome models so watch out. 71G4644 is the most common rubber dome one, but almost anything starting with a 7 is likely a rubber dome.