2003 3500 drw axle swap into 2001 3500 drw

My father totally trashed the rear end in his 2001 dodge Single cab 3500 DRW disc brake. I have a 2003 Dodge Quad cab 3500 DRW Disc brakes (blown motor). I know the DS to axle attachments are totally different and the 2003 has bigger calipers (I will use the 17" wheels). Are the springs/perches the same size? Will it be a bolt in swap? Or will I have to cut off the perches and mounts and relocat them? Am I wrong in thinking that I can have the end cut off one 03 DS and welded onto the 01 DS so that it will attach? Or something of that sort? Not opposed to having a DS made if thats what would be needed. I am just trying to do this as cheap as possible. I don't have the 03 truck in front of me yet, just trying to figure out if this is the route to go or to purchase an axle out of an older truck that is the same. Thanks for any help. Cody