Radiator Install ??

I am installing a 3rd row radiator in my 94 ZJ. I am 99% sure that I located the drain plug on the radiator. Is it the plastic tab that can turn counterclockwise on the lower left of the radiator? I have a Haynes repair manual, but it doesn't really give much to locate it. Believing that i found it, i twisted it counterclockwise and nothing happened. I know that there is coolant left in the radiator, however how do get it to drain? Any help would be great.
-ben-

u have to twist and pull, the stock radiator isn't threaded it uses a O-Ring and is just push into place, just twist and pull.
it is located on the lower driver side of the radiator (94 ZJ w/ 5.2L)