I know that Fender has essentially the exact same model, this is probably either a pre-fender sunn or a post-buyout fender knockoff.
if it is a pre-fender model, it would have JBL speakers inside, probably one of the top 12" woofers ever made. Rated either 2 or 4 Ohm, power handling of around 300W program and 600W max.
if it is a post-fender buyout model, it would still have a decent speaker in it, handling 300W program and 600W max as well, but not handle nearly as nicely as the JBL would.
I personally wouldn't be very interested if it was a post-fender model, but if it is a true SUNN, I'd snatch those up.
Hope this helps somewhat.