With a fixed screen, it can't be later than a K3. Look at the tenth digit on the VIN. It should match the model year for a K series. Anyhow, there is no difference in suspension components between K3 and K4. 10wt is commonly used but fork oil viscosity is a strange number. Different brands vary in the actual effect though they are marked at the same weight. I'll let people experienced in local products answer that. 133mm of air space above the oil with no spring and the tube all the way down is the spec for a DL1000.