Hi ,
Go to CM , find the loco you would change the engine .
Right klick on the loco , in the next screen klick edit and go to edit in explorer.
Then you see the engine and specs .
Do the same with a loco you want the engine and specs from.
When you have the both screens next to each other select only the kuid nr. and paste into the other .
When you did that scroll down on each screen and do the same into the kuid table.
Then commit or start trainz .
I don't know if it works with build-in trainz