Centurion Conversion using bolt on adapters. I understand that these can be unbolted and is basically a SRW Dana 60 axle. . .
as you said, this is a Centurian conversion. that did not come from ford like that.
but I have also seen a number of these for sale, and these are the style I'm referring too when people ask about converting (at least those I have talked too). . .
Which have actual Dually hubs. . .
Though, the above pics are from a BJ Dana 60. . .here is a king pin dana 60 with actual dually hubs. . .
Is it a year split somewhere? If so, where? I only know what I see, and those are what I run into. . .I state neither opinion or fact on this one, just what I have found. . .
Original poster, which one looks like what you have? I guess that answer is the direction you need to take in this matter of conversion