The EQ3 usually comes with a mounting that will take tube rings - from the second photo, the tube sits on it and the holes on the ends will take the tube rings. If you can take another photo - looking straight onto the mounting plate, there is probably two bolts that fasten the mounting plate onto the dec axle. If so, and the spacing is about 35mm - you are in luck. The bolts are likely to be M6 (metric 6mm) - I used to have a mount like this, and I installed a GSO Dovetail mount - like this one. I bought it from Andrews Communications
http://www.andrewscom.com.au/site-section-10.htm
I made up a couple of aluminium washers to suit, so that the dovetail mount does not shift when installing it. Then your C130 should fit in, but might be at the wrong angle, but at least it will be secure.
-John