Reflex struts can be ordered from almost anywhere on the 'net.
I'll get some pics later, so I can have some time to jack up the car for some better measurments. I can't measure the inlet and outlet, as the flanges were cut off to make it fit better. They were originally 2.5" if I recall, which would be fine, but we went for that little bit extra in cutting flanges, and slipping my existing intermediate pipe inside the flanges of the resonator, then welding. The ID of the resonator in the chamber looked to be about 3", and the OD of the whole thing was 6" or so. So call it 6"x24" with 2.5" inlet and outlet, and a 3" chamber (until I can get some more accurate measurments).
It does look very much like the universal 6" round or the race series, but I'll have to confirm the length to figger it out.