Windshield rubber

[Steve Bradley <scscomp@atl.mindspring.com>]

I've got a real puzzler for the list.

I'm repainting and resealing the windshield on my '71 SB. Why do the
parts places show a single "euro" style windshield rubber for 62 -74 but
show an "american" style for 62-70 and a different part for an
"american" style 71-74? The "american" style has the groove for the
aluminum molding strip on the outside.

How could the euro fit all years and the american fit only certain
years?
Did the way the windshield fits change in '71?

Steve B.