I have placed several posts over the years with pictures. My original site for the pictures is gone, so my posts show up without pictures. I now have a photobucket and would like to edit and add the pictures back in to the post. Can this be done??

No, not after a certain time limit.
I think the limit is 15 minutes if I remember correctly.

I think you have 24 hours to edit thats it.. you could add your photobucket to your signature then that would show up in your old posts. that way if they clicked that they could find the picture you were talking about. thats all I can think of unless you responded to each post with the added picture from photobucket thats alot of back tracking though its up to you