canon 600mm f4 IS ? (version 1)

On the version 1 Canon 600mm f4 is. Is there any difference in a lens made in say 2002 compared to one made in 2010. Is the image quality the same and build quality.

Thanks Troy.

As far as I am aware there is no difference in the constriction/performan​ce of any of the Canon Super Tele lenses over their production life, with the possible exception of the Canon 400 F4 DO Mk1.
When I was after a 600 F4 IS Mk1 I just looked at the condition and IQ of the lenses available. The condition varied considerably but the performance didn't.
Others may have more insight on this subject but I found no difference when trying different age 300 F2.8 L IS, 500 F4 L IS and 600 F4 L IS lenses.