I noticed on the 261 oil pan I have not installed yet that there is a well in the bottom with a metal overhang. I'd be guessing but it would seem that if you were mounting the pan, it would have to be put on from "rear to front wise direction" so the oil pump screen and uptake would clear the metal cover over the well. I've never seen one off a truck(other than this one) so that is just my best guess.
There are a lot more folks here with experiance who can better answer your question but forcing it doesn't seem to me to be a good idea.
