Didn't know if you'd seen his previous posts about which models came from Samick, etc,
No, I never said that any Newark St. Guild came from Samick (in Korea), it was a myth on the web regarding Samick. SPG however used to be a former Samick factory but when Samick moved production from Korea to Indonesia former employees bought out the factory and founded SPG. I always said that the first Korean factory Guild used in 2012/2013 was
SPG (
Sound Professional Guitar Co, Ltd.) in Korea. SPG guitars have
KSG (Korea, SPG, Guild) Serial numbers. They make all the semi-hollow models like the Starfire series and the Aristocrat.
The second factory CMG uses is
WMI (
World Musical Instrument Co. Ltd. ) in Korea which made so far all the solid body models like the Bluesbird or the T-Bird. They have
KWM (Korea, WMI) serial numbers. The S-100 switched from SPG to WMI during CMG's ownership of Guild. (WMI has the lid over the pot chamber fixed with 6 screws on the S-100 model vs. the lid with 4 screws on the former SPG made versions).
Now the info that the Jetstar comes out of China is also news to me. And I can't remember a
GY serial number...I make a guess. The
G actually could stand for Guild. And the
Y for
Yako Musical Instruments (Zhangzhou) Co., Ltd.in the town of Zhangzhou city near Xiamen, China. Yako has a 22 acres guitar factory also producing for FMIC (Squier, Gretsch). They ship like 25.000 guitars a month...Look at the Jetstar tuners, they look like Stratocaster tuners, so it could be Yako. I don't think CMG would risk using an unknown new factory. Yako has the FMIC connection to California. And another guess: As CYG (China, Yako, Gretsch) was already used for Gretsch they couldn't use it for Guild, so they used GY instead. Again, just my guess.
EDIT: As of 2020 P.T. Samick in Indonesia is a new additional manufacturer for Guild. See:
https://letstalkguild.com/ltg/index.php?threads/hey-ralf.202089/post-1872910
Regarding the factories see also here:
https://letstalkguild.com/ltg/index.php?threads/where-are-ns-guilds-made.199536/post-1846847
Ralf