Ok, so my bike is a 96 500E but the tank is a newer one from an "F" and I have no front fender or tail plastics that came with it and I have no Idea what color blue my tank is. I'm painting my 90's era palstics to match my tank but what color? Here's what I found... (it's in German but google will translate)
http://www.gs-500.info/index.php?title=Farben
Go to colorrite.com
They have paint codes based on bike model and year.
there is a paint code chart on the WIKI. It uses the same paint codes as colorrite.
I used this link to find what the paint was on parts from other years on my bike. It really is a combination of over a decade of Suzuki parts. Then I used color-rite for ordering as paint changes often. Like a blue offered in 96 is different from my 03 tank and early 90's plastics.