Can Someone Shed Some Light?

Not arguing here, your a vast well of knowledge
Scott's vs gibbons
the nc300 is listed as green the (a) is grey
Note: the only grey surcharge listed in China part 17 8th edition

1949 (1 April-26 July) the surcharge changes to type nc74
(Characters in the right-hand column = (temporarily)
Most noted change I think is the top right :)
1946-48(making this in the wrong category:)
Manchuria (A) RCT#20 -25c blackish/brown-no gum-perf 14
Surcharged 1$ (NC74) in grey
NC300(a)