I was doing the transmission fluid flush on my 86 240 DL sedan as per the 700/900 FAQ. The fluid return line came off very smoothly and the flush went well. Then I noticed that the nipple on the radiator was stripped and the line was not going back on no matter what. The fitting on the end of the line was completely bright red with rust (car lived in Buffalo and Philly for years) and either I twisted too hard or it just was an old fitting. Any easy way to repair this or do I simply need a new radiator? (THis would not be the end of the world, as a very slow leak in the radiator seems to have developed anyways).