Leaking Trans cooler fitting (top)

[87MJJeep]

I put a new radiator in my 4.0L Comanche Easter weekend.  I put in a 92 P/N radiator to switch to an open system.  Based on comments in the reviews for the part, it is a Spectra-made radiator.  It came with a male/male (?) fitting screwed into the top opening for the transmission cooling line.  I just removed it and screwed the old line's fitting into the new radiator.  The threads appear to be the same, but it didn't screw in very freely though it was not binding.  I removed it once, and the threads looked OK. 

 

I have always read to not over-tighten these types of connections, so when I fired it up, I was way too conservative.  It was dripping a few drops a second.  I have gradually tightened it further in 3 stages.  It now is just a weep.  If I wrap a paper towel around the fitting, it catches what little is coming out.  

 

Do I need to keep tightening it bit by bit, or was I supposed to use the male/male fitting that came with the new radiator connecting the 87 line to the 92 radiator?  It would have required a female/female adapter for the factory male fitting.  

 

Thanks for any advice.  Meanwhile, I'll drive it with its "diaper" wrapped around the line.  LOL