Hi, i have a jeep Grand Cherokee Laredo 4.0l from the year 2000. and Im trying replace the radiator with a new one bought online. Was going smoothly until i tried removing the transmission lines, which look to be some kind of compression fittings. Its proved to be nearly impossible. I have been using vise grips and anadjustable wrench. Would like to try to fix this this asap, What should I do?

 

what should i do?

 

OK-So, I assume the fitting still looks like your picture. I don't understand why the threads look so mashed up. I would soak the threads and the tube going to the nut with PB Blaster overnight. You should always use a flare-nut wrench that fits that fitting and not an adjustable wrench or the brass nut will deform. Invest in some of these if you're going to do brake lines or transmission cooler lines.
If all else fails, you can try to take the fitting off the radiator while holding onto the compression nut with a wrench.

 

That nut looks like steel to me. The one on my XJ is steel as well. The threads are mashed from the vice grips that the OP mentioned.

If the overnight PB Blaster soak that 67 GMC suggested doesn't work, I would try getting that fitting hot with a torch then quenching with water to break any galvanic corrosion free. It will get hotter if the radiator is already drained. It might melt the plastic tank on the radiator, but you're replacing it anyway.