Interstate rear calipers are different from Tourer/STD calipers. All front calipers
are the same. Years don't matter on Tourer/STD calipers.
-Mike "this is my story and I'm sticking to it

"
I think the rear calipers are the same. The IS rear caliper mounting brackets and discs differ from other models depending on year.
EDIT: Except, I think IS rear calipers are black instead of aluminum colored.
I think I'm recollecting correctly.