It's highly unlikely you can remove the oil pan from a 1994 Dodge Ram 250 van without loosening the motor mounts, at least slightly. The clearance between the oil pan and the frame/crossmember is usually very tight. Even with jacking the engine up slightly, the motor mounts will likely need to be loosened to provide enough movement to get the oil pan out. Completely removing them isn't always necessary, but loosening them enough to flex the engine slightly is almost certainly required.
Trying to remove it without any movement of the engine risks damaging the oil pan or surrounding components. It's far safer and easier to loosen the motor mounts – even a small amount – to create the necessary space.
