I dont know about 04 and 05, but on all my 03's, You need a hex bit for one end and unscrew the loop bolt, Then the cross bar will pop out/ off the little bracket deal, then at the rear of each rail, there should be a little snap in cap on the inside where the bars slide. I can grab pics of everything later today, I just pulled some from my parts truck last night, My Mounty didnt come with cross bars, which I swapped in when I got it.
Look for the little 1x1 clip thingy where the cross bars stop when all the way back. Or the blank plates since you dont have the cross bars yet. You'll have to take the covers off the plate things that are there, pull them out of the end one "end" of the plate at a time, it flexes. Same with the new pieces for the cross bars, then pop the cross bars back onto the bracket thing with the hex head screw, then the loop bolt, kind of a pita to not knock the little nut thing off once in there. If I get pics together before you figure it out, You'll see what Im talking about.
If yours doesn't have the little clip thingy inside, I'll take pics of my end covers too, and if they match yours, I'll send them to you for whatever shipping costs. I just popped mine off to save them for whatever. Dont know if they'll work for what you need if yours dont have the little clip in dealies but if I can help I will.