Well we are going to have a quiet little chat about F100 door pillar/step rust out. Just about every F100 I have owned or pbserved seems to have signs of rust showing in the door pillar/step area. I decided one day to adjust the drivers door since it had a little sag in it and would not close nicely. When I decided to loosen the hinges and make the adjustment I discovered 2 bolts in the hinge were frozen. I used some WD40 and gave it a little time but no luck. On further inspection I discovered not only was the rust out in my step getting worse but it had spread to the bottom inside of the pillar. My advise to anybody who has minor signs of rust out is to immediately complete the following so maybe you will slow it and not need to do what I have had to do to fix it. Firstly drill at least a 3/8" diameter hole on th underside of the pillar so any liquid getting in can drain out. Secondly inspect your gusset that braces the pillar base under the vehicle and wash it out with water, mine was caked with road salt and gunk. At this point you are satisfied that you have no major rust out issues I suggest clean up and spray something designed for the outer surface to help keep road spray and future gunk from getting in. With respect to your gusset may I suggest that you use what ever silicone style product you are comfortable with and seal all the openings facing the tire side so the tire can not flick water and road gunk into these openings. In my case it was too late although I plan to seal all these opening up once I have completed my rust repairs. To get the door off, I had to gently heat the center recessed bolt from under the fender to get it to move and undo. The bottom bolt on the lower hinge was frozen so bad and would not budge. I ended up removing the rusted sheetmetal and a little extra to gain access into the pillar cavity, where I also had just enough space to get some mild heat onto the nut and free that bolt as well. Remember to ensure you have a wet rag and some back up fire fighting equipment should things not go to plan. The remainder of my repairs are in the pic's plus some shots of my original damage. My repairs did require me to cut off the gusset to access the sheetmetal. I will just weld it back in later. I got to say if I had know and given more thought to this problem earlier I feel I could have saved myself a lot of time and effort. Damn shame Ford did not do a better job with the construction of these pillars and bracing. It seems it almost encourages the rust out. I am not going to make a meal out of this but if you go this far it maybe adviseable to work out a way to seal the vertical opening between the fender and the cab/pillar outer portion as well. That can be another thread some other time. Any volunteers???