a 1/2 inch line wrench and a 5/8 open end is used to take off the transmission lines.
USE A LINE WRENCH.
trying to cheap out here will probably round off the radiator nut.
Hold the larger nut with the 5/8 and loosen the 1/2 inch one so it spins.
Then, loosen up the 5/8 all the way out of the radiator. Keep an eye on the line and make sure that 1/2 is spinning with the 5/8 so you don't kink the line.

Owner caption January 2010 · Photo 8 of 19