I'm not sure if I had all of them in ME2, and thus I don't know if they are all there for me to find in ME3, but here are the collectibles I found on the Normandy:

Alliance Shuttle - CIC: between War Room and Galaxy Map

- CIC: between War Room and Galaxy Map Destiny Ascension - Crew Deck: Life Support

- Crew Deck: Life Support Turian Cruiser - Engineering: Subdeck Stairwell

- Engineering: Subdeck Stairwell Space Hamster - Engineering: Subdeck Stairwell

- Engineering: Subdeck Stairwell Shadowbroker - Engineering: Subdeck Stairwell

- Engineering: Subdeck Stairwell Sovereign - Engineering: Subdeck Stairwell

- Engineering: Subdeck Stairwell Freighter - Shuttle Bay

- Shuttle Bay Quarian - Shuttle Bay

- Shuttle Bay Alliance Cruiser - Shuttle Bay

- Shuttle Bay Geth Cruiser - Shuttle Bay

- Shuttle Bay Normandy - Shuttle Bay

That's the master list of what I've found so far, but I also broke it up down below with maps.

Also of note is that the model for the Alliance Kodiak was for sale in my game from Kassa Fabrication shop (accessible at 10% markup from the terminal in the Shuttle Bay). I am not sure if that's the only location for it, or if that's simply where you buy any models that you didn't have from your imported save.

Combat Information Center

Alliance Shuttle - Between War Room and Galaxy Map

Crew Deck

Destiny Ascension - Life Support

Engineering

Turian Cruiser - Subdeck Stairwell

- Subdeck Stairwell Space Hamster - Subdeck Stairwell, runs across floor, sometimes hides

- Subdeck Stairwell, runs across floor, sometimes hides Shadowbroker - Subdeck Stairwell

- Subdeck Stairwell Sovereign - Subdeck Stairwell

Shuttle Bay