What is the best way to repair this other than trying to replace the lines. They are the transmission cooling lines. Also how do I get them apart?

 

Need the special tool to release them. (3/8ths trans line tool, local parts store will sell 'em. don't get the multi-tool, they just don't fit into the tight spaces.) Gotta remove the big clip that holds them together, insert the tool, push it into the end of the large connector as far you can, then shove the connector ONTO the line a bit further, while holding the release tool in place, then they slide right off. (supposedly.)

I would just get some 3/8ths trans-rated rubber hose, remove those lines from the radiator, cut them at the other end, flare the ends of the lines a bit, and just double hose clamp them in place. That greenish, corroded feller on the upper line, where it joins the metal part of the line coming from the trans is a check valve. You want that gone as well. They like to clog, stick closed, and then your trans burns up.