Let me see if I can guess where you got all these beauties:
Cotton Belt L-1 4-8-4 Northern 817 from K&L Trainz
Streamlined Reading 4-6-2 Pacific made by leeferr that's on the DLS
An unidentified reskin of thecowboy's Frisco 4-8-2 1522, though most likely euphod's reskin into Santa Fe #3700
Central of New Jersey P7 4-6-2 Pacific from Auran/N3V
Texas & Pacific 4-8-2 Mountain from the old Trainz Forge website
Pere Marquette N-1 2-8-4 Berkshire from K&L Trainz
Southern Pacific GS-4 4-8-4 Northern from Jointed Rail
Southern Pacific MT-4 4-8-2 Mountain from K&L Trainz
Santa Fe 2900 Class 4-8-4 from The Backshops
Streamlined Baltimore & Ohio 4-6-2 from K&L Trainz
Union Pacific FEF-3 4-8-4 from current Trainz Forge website
Streamlined Burlington steam locomotive is the only one I don't know where it comes from. However, it looks like a reskin of leeferr's streamlined Reading Pacific
Nickel Plate S-2 2-8-4 Berkshire from K&L Trainz
Milwaukee Road A 4-4-2 from K&L Trainz
How close am I?