I came to this forum because I'm looking to buy Underwood  No 5 and I'm looking for info about its variants.
I see No 5 with white glass keys, black glass keys, plastic keys. I'm sure that there were more differences than just keys as design progressed over the span of years.  Where I can find differences between those variants and their years of manufacture? I tried Google, but didn't find anything specific about variants of No 5.
Thanks all.