440 will not fit in duster ? ?? need help assap doing motor now !!!

sounds like you are doing something very wrong. i would first sort out if you have a engine mounting issue or a header issue. take your headers out and leave them out.
now put the engine in and see if it bolts in.

did you trim your k member like the instructions from schumacher tell you to do?

post some pics or get somebody to physically help you who knows mopars before you ruin anything else.