Saw the title and was just gonna keep it simple saying
Rule of thumb
If it's got a serial starting with "T"
or
3 holes drilled brake bridge
or
Flattened inner face on the seatstays
Then you've got a 100% full chro-mo Supergoose
That should be enough knowledge for starters
When you get a serious addiction , you too will be advising people with a 5 page full on anorak reply