What available reference provides the actual assembly or "date of birth"?? Is it a publication or something available on-line?
Bruce McCalley's "Model T Ford, The Car That Changed The World" lists assembly dates by engine number. Of course, this is useful only if your TT has its original engine.
Starting in late 1925 the engine number was also stamped on the chassis, but apparently this practice was not universal.
Aside from the above, it's pretty much a guessing game. There usually are "early" and "late" clues. Some clues can narrow it down. Examples are:
1. Beads on the rear end clamshells at the axle tubes, early truck.
2. Short chassis rear cross member (1 hole) early, long (2 holes) late.
3. Wood or metal dash.
4. Short or tall radiator.
5. Patent plate.
6. Steering column.
7. Differential pinion shaft (2 gears) or spider (4 gears).
8. Short or long running boards.
9. Round or oval gas tank.
That's what comes to mind right now. The problem is that not all changes were introduced at all assembly locations at the same time. Phased out parts were used until the supply was exhausted. Of course the biggest problem is that most of these trucks were fixed and repaired over 90-100 years with whatever could be found. Making them serviceable was much more important than "correctness".
I hope this helps a little.
Thanks, guys. It's time for me to do some more reading.