Weird C-130 variant

Saturday, I was helping a friend move near McDill AFB in Tampa. I heard the unmistakeable sound of a C-130 and walked out to see the thing maybe a few hundred feet up flying over. I want to say that the plane had a dark gray paint scheme.

Now, I have seen lots of C-130s, but this one had a feature I had never seen before. On the vertical stabilizer above the horizontal stabilizers, there was a box unit that appeared like something you would see on a box kite. It had a look almost like world war 2 bomb tail units - very square but with rounded edges at the corners. The box appeared to be equally split on both sides of the vertical stabilizer.

Any ideas?

I’m guessing some kind of aerodynamic testbed, but I don’t know why they’d use a C-130.

Perhaps it was a variant of the EC-130

Reference:

Maybe a NASA plane?

They do aeronautics research.

Nailed it in 1. Having previously lived near Davis Monthan AFB in Tucson, I would have said no way to EC-130, but that photo is dead on.

Thanks!

Now that the question’s answered, here’s my favorite Herc. 105mm howitzer, baby!: https://en.wikipedia.org/wiki/Lockheed_AC-130