Tonnage Ratings in Loco Model Names?

[Amalynn]

They pulled 1-2 cars.

While freight would certainly be heavier and pulling it around would require more power, or fewer cars behind the locomotive, I know that I had seen footage of a 10-15T DDT pulling four cars behind it on an excursion passenger train (a short combine, two coaches, and a caboose). Admittedly all five pieces of stock in the train were 36" narrow gauge, but I'm curious to see how much a DDT could pull at most. I am a very big fan of watching critters zip around and have wanted to model several of them. Model Power used to make one, but from what I understand they are out of business now.