How can you destinguish each model
First look at the Bell of your horn.
Is it a splitt bell design (Low B and Bb on the opposite sides of the bell)?
Then it can be a Handcraft, Type-writer or Troubadour.
Are both keys on the same side?
Then it can be a Handcraft Imperial, Handcraft Committee, Comm-II, The Martin, Magna, Indiana, Imperial, Medalist.
Splitt bell design?
The Troubadour has only two side palm keys, the others have three. Sometime the name Troubadour is engraved.
The Type-writer (official name Master) doesn't have normal palm-keys. They are all round with pearls.
If it's not one of the above, it's a Handcraft.
Both keys on the same side?
Look at the engraving on the Bell.
The Handcraft Imperial, Magna, Indiana, Imperial and Medalist all have their name engraved.
City scape engraving, also called search-light engraving?
You've got yourself a Handcraft Committee.
Lion and Crown engraving, with Martin verticall on the bell?
It's a Committee-II. (Also the text Comm-II can be found on the body)
Is it engraved with the text "The Martin alto", "The Martin tenor" etc..
You've got my personal favourite a The Martin. Also called Committee.
Also compare the keyguards with the ones pictured in the galleries.
All non-splitt design Martin models have very destinctive keyguards.
Is it an (Handcraft) Imperial?
Look at the serialnr on the body of the horn.
Is it around 100.000 then it is a Handcraft Imperial.
Is it way lower then that or in the 300.000 range then it is a (modern) Imperial.