Classic & Vintage - Trek: logo on fork crown, not on seatstay

I'm curious about an older lugged Trek someone has chained to a tree near my house. Simple logo on the seat tube, just the word Trek in white, no backing or gold band, but a red and black stripe above it, and no decals otherwise, that I can see anyway. 'Trek' is incised in the fork crown, but not on the seatstays. I only looked at it briefly, but it has a hodgepodge of components: Weinmann brakes, Suntour FD, Huret rear. Triple chainring. Rear rack which looks original. If it's still there tomorrow I'll get a pic. Looking at the vintagetrek site I can't even find an age range to look into. Can anyone point me in a direction?

It's not for sale and not abandoned...I don't think. I'm just curious.

If you can, get the serial number.

Bike is still there and it being fairly loose on its cable (and it's no longer a. dark and b. raining) I took a look for the SN. 003643 followed by a W and a T off at an angle. Discounting the letters, this SN would make it a 1981 model 410 in a 22" size which seems about right. I'll be keeping an eye on it. We are close to an entrance/exit for the Chicago 'El' which gets more traffic these days, so parked bikes go along with that. Chaining to a tree seems a little careless though!

Bike was stolen last night. :( Unless it was the owner who came back and cut the cable lock and left it in the grass. I was trying to keep an eye on the bike--it was visible from my wife's home office--but obviously couldn't do it 24/7.

a pity. but the owner couldn't have valued it highly, if it had been left there for that long...