I want to swap the 5.9L LA engine currently in my 1986 Dodge Ram Van into a 5.9L crate Magnum engine for more power. I've read online that they have the same bottom end but have different top ends, so my concern is does it fit and everything closes?

Also, I know that it will be a pain to swap since the engine is inside the cabin, but I will find a way of swapping it.

 

The magnum has different mounts but earlier blocks where cast with both motor mounts boss's. You will need to use the flexplate/torque converter for a magnum also.