This one fascinates me because of the holes in the head tube. Could these have been added at a later time or do they indicate a pre 1980 model?

Anyway, below are photos owner sent me of the serial number. Anybody have any idea what we're looking at here?

Per Vintage-Trek.com

FOREIGN-BUILT FRAMES AND BIKES AFTER 1982

Three different serial number forms have been submitted for 1983 Trek Model 400 frames. One, marked "made in Japan", begin with JS followed by six numerals. The SN was located on the bottom of the bottom bracket. A second serial number is 81765. According to the Trek-provided SN list, this corresponds to a 22" (22.5") Model 400 frame made in 1983. This SN form is for frames/bikes made in the US The number was marked on the bottom of the bottom bracket. The third number is 403300950, which indicates foreign built, but the nation of origin sticker was missing. This number was marked at the bottom of the down tube. It is likely this 400 was made by the same manufacturer as the 1984 bikes described in the paragraph below. For the 1983 Model 400, it appears Trek used three sources for their frames or complete bikes.

Several 1984 Trek 460s, 420s and 400s have been reported with 9 digit numeric serial numbers stamped on the lower seat tube instead of on the bottom of the bottom bracket. These frames, or complete bikes, apparently were made in Japan by an outside contractor. The numbers submitted are in the range of 401000000 to 440000000.

An 8 or 9 character alphanumeric code was used for mid- and low-level frames subcontracted in Taiwan. Most of these bikes were labeled "Made in Taiwan" (although the sticker often is easily removed). This form of serial number appears to have been used during the period 1987 to 93. The number leads with a T (for Trek?) then a numeral, one letter or two, then five (sometimes 4) numerals. Sean Hickey suggested the first numeral is the year of manufacture, and the letter is the month of the year (A - L). This is confirmed by serial numbers that were submitted by other Trek owners. If there are two letters after the year numeral, the first is the month. The second runs from A through at least Y. It might be a way of extending the 5 digit number series by a factor of 26.

A later 8 and then 9 character alphanumeric SN scheme, used beginning in about 1989, also begins with a T (for Trek?). These later T numbers were used on lower level subcontracted frames but do not follow the 2nd and 3rd or 3rd and 4th character date meanings above.

Beginning in about 1993 (model year 94), an 8 character alphanumeric code was used for some bikes. It begins with G and another letter (e.g. GN, GQ, GR, GS, GU, GV, GW, GY and GZ). These are followed either by: 6 numerals, or a numeral and a letter followed by four numerals. The first numeral in the SN may be the year of serialization.

Interesting. Did these bikes have screw-on badges or were the holes added by a previous owner?

must have been added later. those holes look too close together to be 70s Trek badge. Plus the made in tawain sticker. Also the riveted on cable guide on the bottom bracket..sure it's a trek? We're the mid 80s Elance models made in tawain? I dont have a Trek past 84 other than my 97 520. so I'm not sure

ya, the holes look a lot larger than those on my '79 710. There's "TREK" stamped on seat post lug so I'm pretty sure it's a Trek.

My 86 400 Elance doesn't state where it's made- My assumption was that the frame and rear end were separate assemblies, and then brazed together in Waterloo. I don't know about the post 87 400 and 600 series bikes.

1988-90 Trek 330 was produced in Taiwan, and one color those years was red/white lettering. The badge would have been stickered/glued so those holes are interesting/mysterious for sure.