w150 door not shutting right
 

My door is not shutting right. I have to slam it to shut it. I had an ex body man come over and he told me what to do but I forgot! My uncle said the door never shut correctly and I really want to fix it. Have any tips or tricks? The truck is an 83 prospector 4x4 by the way.

is the door sagging a little, like from somebody hanging on the door? I used a block of wood under the door and gently jacked it up on my 50 Plymouth, it worked....fred