Don't worry about it, I was curious more than anything else. If you look at CLD's picture, you can see the port is really what looks like a triangular support, with holes cut in the baffle under it. So far the 415M's I have seen for sale in recent times all appear to have this port configuration
Mine isn't so much a build as a tribute, I'm repurposing an old Peavey 2x15 cab ripping out the baffle and putting in a triangular one to house four speakers. This gets round the wifes 'no more speakers in the house' rule, as it won't be another cab. It's not quite as deep as the Sunn cab, so I'm going to have to fudge it a little I think. All that information on how the baffles are mounted is awesome though. I'd have thought they just bolted it straight to the cab, but they've left it almost floating. Less angle cuts to make I suppose, just need to groove the back support, the rest is all straight cuts.