If this Yahoo Japan listing is correct, there were two series of the KGW gauge clusters. The original, which was discontinued a few years ago, was heavier and made of more metal and glass pieces. The second, and current, series is lighter and uses more plastic.

The listing states (Google translation):

"Production end out-of-print is an ultra-scarce goods.
The current product has been used many plastic parts, initial product ramp around, texture is quite different in the metal also make the instrument panel around.
Meter glass also I feel the weight that was heavily to have to hand in hard glass. Hard glass, SUS304 hairline finish specifications, I will probably difficult to obtain.
The initial made of rare parts that are no longer apparent much current. Towards the collector looking for, to dress up around the meter, and how might it be."

http://page5.auctions.yahoo.co.jp/jp/auction/e154836199

This might explain the conflicting descriptions found on-line regarding whether the KGW vs. RS clusters are the same or not. Some say the current KGW clusters are the same as the RS clusters. If true, which size of Adam's panels would fit?

I ordered two sets from Adam (one of each) because I have no clue what cluster I really have or which size it will take--and Adam's lenses are 1/3 the price of the anti-glare KGW lenses AND appear to be FAR more effective in reducing glare based upon the on-line photos I have seen.