it's not fun, but you can get at most of them from the back through the kick panel opening - might hafta take the door off the hinge on the door side, tho those bolt can present worse problems - once the hinge is out you can repair the cage and/or replace the nut - you do need that adjustment, so don't weld them in place - I've got a couple on onea my trucks that're 'uncaged' and just hafta be put on last from the inside - if the pockets are rusty, you can get at the lower ones by coming thru the front of the pocket, then rebuild the pocket
Bill