I think it's been documented that Okanogans are some of the heaviest TCs. I think I remember some being over 6000 loaded. With the wrong load in the cargo hauler, it could be pushing 7000 lbs or more with the tongue weight.
As far as the truck goes, my F450 wheels have 8 round holes rim, so it is definitely different than that. My guess would be F350. I don't know the difference in frame between a F350 and F450, but my guess is they are different given the F450 weighs about 1000 lbs more.
One other thing I noticed is that the front tiedown mount is pretty far back compared to a normal Torklift. I'm not sure if that matters or not either.