Bjorn,
What is wrong with the doors, other than the two guides? I called either Saturn or Clark (memory going slowly) and it was about $40 per door.
Don't know what a replacement door would cost. When looking for new wheels a place here in Colorado had two five ton cabs on their lot. I think they both had their doors. BUT you would still need to replace the guides, as they were trashed. I couldn't even roll up the windows because the handles were missing.
If you decide to get the guides, pictures please. I am going to be doing this, but it's down the list a ways. Things like new wheels and tires, turn signals, bottle jack, impact wrench are first. Then some touch up paint in the cab and some insulation. THEN maybe the guides in the door, but only after replacing broken glass in windows...
It is a never ending journey. Keep us informed.
jim