You can just push that plastic collar back. There should be a hex fitting under it that you can then take a wrench to and disconnect.

 

the tank for the trans is inside that radiator, and seperate from the engine coolant.
no offence, but did you not notice how the engine coolant isn't red like trans fluid?
you can use a piece of flared brake line with the fitting, and screw it into the rad for drainage (this is in reference to the fitting swartlkk was refering to). just bend the brake line where you need it, and run a rubber hose down to the bucket.

 

Many thanks to swartlkk and old skool but have two questions to relieve my confusion---

----I have a removable clip under the plastic at the fitting -dont I just remove that and pull out the line?

----if the fluid comes out of the upper radiator transmission cooling line fitting does that mean the transmission fluid flows from the trans to the bottom of the radiator and up to return?

 

You are on the left hand side of the radiator looking at it from the front facing the truck correct? All of these connections I have ever come across have been threaded in for the transmission lines. If you have a 4wd, on the driver (right hand) side of the engine compartment (again, looking at it from the front of the vehicle), the oil cooler lines will be a clip in style connection.

 

If it's anything like my '93, the oil cooler lines are on the driver's side and the tranny lines are on the passenger side of the radiator. Both thread in on mine; no clips.

 

i did my tranny filter and fluid not too long ago, dropped the crossmember, took a sawzall to the exhaust.. had to fire up my welder but it was still better than a slipping tranny.