Hardly a Fook-up.
Just good stock control. You often see early and late in the production models from Kawasaki using older or newer parts.
Probably when that "Kansai"/ just in time inventory control system they were taught by the Americans screwed up. No stock of the new tail light design for the new model. OK Lets not hold up the production line , use those old model ones , till the correct design arrives.
And at the end " Hmmmm , we have had less orders for this old model than forecast. So we have too many of the old speedo design. OK, just use some of them on the new model at first "
If you follow ?
Another example. I had a mfd 1974 S1 back from the States one time. It all added up to an S1-B. Speedo having different graduation markings from a C etc. Darnit, I even painted it green before checking the numbers to realise it was a very early C. With B parts fitted from new. ( And just ask Wolfie. He`s adamant his S1-C has had chromed headlamp ears from new. But every trainspotter will disagree........
)
Fact is. The Factory would fit whatever kept the production line going. They were mass produced units with an expected planned obsolesence factor . They didn`t expect us to be debating the widgets 40 yrs later !!!
Oh. btw Johhny. This S2 I`m offering for your nightmare bike ( Caw, take it of yer `ands mister. Scrap value
) This S2 is garuanteed to run forever, and never break down !!!
Looks like it has been de-coked recently (In miles not years) Only one baffle is stuck - along with two of the cylinders. Tank is perfectly clean inside - not out though 
who can date them 
