Someone with more knowledge of early Sunn Amps & speakers would have to answer your question definitively, but I do know that my Sunn Solarus has output jacks for 16 ohms or 8 ohms, and the 2 x 12 that came with it is a 16 ohm cab, so I would think that it is possible that your cab could be 16 ohms. Please wait for someone with more knowledge then me to answer your post, but I think the only way to know for sure would be to look and see how the speakers are wired.
Check to see, if you can tell, what ohms the other speakers in the cab are to be sure someone didn't just stick a replacement speaker in there.
(I think that the Celestion speaker must be a replacement; I don't think Sunn used them back in the day, but someone else needs to verify that because I am not sure of it).
If all the speakers are 16 ohms, I don't think it is possible for the cab
to be 8 ohms. I think it has to be either 16 ohms or 4 ohms.
Two 16 ohm speakers wired together in Parallel = 8 ohms. Two sets of those wired together in series = 16 ohms.
Two 16 ohm speakers wired together in series = 32 ohms. Two sets of those wired together in parallel = 16 ohms.
Two 16 ohm speakers wired together in parallel = 8 ohms. Two sets of those wired together in parallel = 4 ohms.
