Trek frame serial number puzzle

[glasgowcyclist]

I have a Trek 1000SL which I thought I bought in 2005 or 06 which has some paint damage I wanted to touch up, so I thought I’d get accurate paint match info from the manufacturer by supplying the frame number. This has thrown up some confusion which is really bugging me now!

I know the format of WTUnnnGnnnnZ means it’s a Trek (WTU) built on ‘nnn’th day of that year, G is build factory, ’nnnn’ is the frame number and Z is the build year.

According the Trek Archive model info, the colour scheme for my bike dates it to 2006 but the Z suffix dates it to 2005. To make things even more confusing, I have found my original, hand-written receipt from the dealer showing I bought it in August 2004!

There are other identifiers within the specification, such as mine having the Bontrager carbon forks and Bontrager aluminium seatpost which suggest conflicting production years.

I’ve put my frame number into Trek’s site but it says it isn’t recognised. (The number on the bottom bracket definitely tallies with the receipt, and I’ve tried swapping O for 0 where that occurs.)

I’m not so bothered about the paint match now, as Trek say they can’t provide that info for such an old bike.

Can anyone solve the puzzle?

Here’s the model I have:

 

[Mike_P]

If it wasn't for the receipt the answer could have been it was a frame built for stock and painted at a later date.

 

[Cycleops]

Snap. I've also got one. I always thought it was 2007. I rescued it from under a pile of bikes here missing a rear wheel for about £20.
It's scratched to hell so I painted the rear seat and chain stays Matt black
Wheels have been rebuilt with wider rims to take 28c tyres ( fit just about). Rear now has Deore MTB rear hub ( can't be fussy down here) to accommodate a 9 speed cassette with Tiagra brifters. Has the Bontrager carbon fork and carbon seat post. Cane Creek headset
Absolutely love it. RD is a RX100 now.
Can give you the frame and serial nos if you like.

 

[glasgowcyclist]

Can give you the frame and serial nos if you like.

I’d be curious to see if they are similar to mine, so that would be good if you don’t mind.

 

[Cycleops]

04200092A
WTU

TBI - 0405
GP 604646

SERIAL NO:
GI 037792

 

[glasgowcyclist]

04200092A
WTU

TBI - 0405
GP 604646

SERIAL NO:
GI 037792

Thanks, that’s interesting.

My frame has TBI-0405 as well, maybe that’s the model identifier.
Then GU400649.
WTU148G0685Z.

Your frame number (WTU04200092A) suggests it was built on 11 Feb 2006.