One of mine is leaking too. I have new ones but have not changed them yet, but helped a friend change his on his Sierra.. My trans lines leaked the same way at the hose ends where it goes into the fitting. The trans lines are real tuff to change because of the exhaust blocks access to the fittings on the trans but engine oil cooler lines are fairly easy to get to just a little tight where the line supports or clamp the hold the lines under the motor.
Start with line on the motor, remove the wire clips that hold the line into the fitting, wiggle it back and forth pulling it straight out. Have a rag or container ready as the oil will flow when you pull the second one. Let the oil drain for awhile before you pull them at the radiator so you get as much as possible from the cooler. Put in the new ones and your done.
I was going to take my old lines and replace the rubber hose with braided steel lines and AN fittings. And then if it ever starts leaking again change the out or if I'm bored one day...
Randy