My guess would be 2002. What does the little sticker on the left chain stay say, built in California USA?
Those stickers where on GT bikes assembled in the GT factory. The original company was taken over around this period and don‘t believe later bikes had that sticker. The frame was probably made in Taiwan due to the the round end cap on the top tube.
Those GT’s rode well and had good geometry . I’ve covered most of the north and sound downs on one, although a different model to yours.
From an old MTB thread webpage 🤷♂️
“
#3 ·
May 3, 2006
Correspondence by Dan Garcia of GT regarding Serial Numbers
I have been trying to research the same thing. I found this letter or email from Dan Garcia from a webpage awhile back and I copied and pasted it to notepad for reference. The webpage was a GT/BMX oriented page as I recall. You will see references to BMX bikes toward the end. Unfortunately I don't have the website link to credit and I apologize. But here it is:
"If the bike frame was manufactured at the Santa Ana CA facility, the first three or four digits of the serial number should be letters abbreviating the model or size of the frame such as "XL", "XXL", CR24, or something like that.
The next part of the serial number is eight numeric digits. The first four numbers should be a two digit month followed by a two digit year.
The last four digits are the serialization digits 0000 to 9999 depending on what number the frame was of the years production.
If the frame was made overseas in Taiwan, it gets more complicated. If the number starts with a K, the frame was made by Kinesis.
That's the only one I remember off the top of my head.
There were at least four companies in Taiwan that made the GT lines :
Robinson, Dyno, Powerlite and Auburn included)
The first digit would be a letter designating the factory that made the frame. There might also be a second letter digit specifying the factory that assembled the bike, if applicable. The model and year of production was also coded by a letter, so you won't be able to spot a two digit month and two digit year.
Before I left, I was writing a specification to standardize all of the serial numbers because GT was starting to send most of its US production to other US fabrication shops.
The information might also come in handy for deciphering other makes because the factories in Taiwan make bikes for a lot of different companies”