Stubbs67,
If you do choose to replace just the peice, be sure to have a cold rag near so you can cool the metal and take your time welding. Do a little then cool it off quick because if you dont you will warp the heck out of it. What I was saying about replacing the entire skin on the door was so you wouldn't have to weld it. What you do is take the old skin off the door, place the new one on then get yourself a Body Hammer and a mall and knock the new door skin lip that holds it on over the lip of the inside of the door. I will post a picture to show you what I mean. Once you have the door skin in place then you put some Trench putty around the inside of the door where you hammered the door skin on.
The only reason we welded the backside of the door is because the peice that the door skin went on was rusted through (the inside of the door).