You are looking at a PART for your classic Lionel SD-18 diesel engine, perhaps others. It is an original part.
May fit other diesels, but that is up to you.
Look at all the parts that are here:
- Truck sides
- Motor field
Just add a motor, and you are good to go!
Note that the bottom has the number 8855-125. That number may be for the base part. I am not sure. The Lionel service number is 8855-100.
CONDITION: C-7. Looks great.