Trek Bike Serial Number Lookup
If you look at, you should be able to figure out which bike is yours. It can't be a 1974 tx900 because Trek did not exist before 1976. That particular tubing was used in 1983-84. In 1984 the word TREK was cast into the seat post lug. I can't tell for sure, but your bike seems to have some word cast into that seat post lug.
Voyageur r21. Year: 2012 Brand: Schwinn View Details.
It looks to me as though it says TREK. 1984 would also agree with the badge. But then the tx900 wasn't made in 1984. Your bike must be one of the 'upper-level' models listed on this site.
I would also point out that your frame has brazed on brake cable guides. Bikes in the seventies tended to have clamps for the cables. I can see why you are confused about the year and model. It doesn't seem to match any of the standard bikes described on the Trek site. Bikes in 1984 had the model number on the frame decal.
Yours seems to have a 1981-type seat post decal only. Have you measured the seat tube? The head tube is very big, suggesting this is a very, very tall bicycle. Did Trek ever do one-off custom frames? I don't think the serial number is going to answer any questions, because it seems to be unique. And, frankly, this bike seems to be unique. My guess would be 1980-85, possibly repainted, in which case the decals might not be correct.
Or, possibly a special order extra-tall frame, in which case the decals might not match the 'standard' configuration. I would review the components very closely (assuming they are original) and see if there are any bikes in the 1984 catalog that might match them. Lal kitab book in bengali pdf ebook reader.