I want to say that they are the same. But I am not sure. Have you done a search on this? I would...you will be surprised on what you can find. IF you want dsm 450's let me know. What year is the obd1 motor. I think as long as it is a gsr from 94 you will still be ok but b17 would work but might have a different size than the b18c1. are the plugs the same?