Hi All,
Found an interesting article from profaudio1 a power seller on ebay, on identifying Canon EF 28-105mm f/3.5-4.5 USM lenses and the many variants of the USM and USM II lenses.
As it is ebay copywrited I am simply pasting the article link.
http://reviews.ebay.com/Canon-EF-28-...00000004237669
For any users that own this model, they will tell you that it is dam hard to tell the difference by the labelling on the lens housing, as Canon included most of the model info on the retail box and not on the lens.
Unfortunately not many people tend to keep the box, so when you are thinking of buying this lens as there are five derivitaves of this lens, this is a good starting place to help you identfy most of the early models and nasty versions.
Happy reading.
Vandemonsland (Des Mo)