Information on this guitar is very limited. It is a separate model stating the model clearly on the headstock.
Information I can find suggests that only 50 of these were made all in 1984. In January 2017 one was offered on Ebay USA from a Japanese seller at $1324
buy it now price. The serial number conforms to 1984. I have now seen pictures of two of these.
The scratchplate has been lost on this guitar.
The pictures below don't really tell us much more, I can see that the fretboard is rosewood and the rest of the features also
look similar to the 1300 I am unable to see what makes this a different model, except the colour. The Sunburst on the 1300 is a tobacco
sunburst whereas this is more like a Cherry Sunburst.
Leon from Japanaxe who has a great Yamaha site in the Netherlands, see my links page, has made the following comment
I'm not sure but some claim the W in SG1000NW stood for wave maple referring to the striped maple. Looked up some SG1000NW's
and they all have a striped top.
The SG1000NW was a special edition march 84 guitar so about the same period as the SG1300W. The SA1300W seems to be striped too.
Hypercarrots from the Yamaha forum has found some more pictures of a 1300w serial number 136364
and provided a link which says that this model was first released on the 1st March 1984 at a price of 130,000 yen.
The rest of the pictures.
Some pictures of one with the pickguard