Thank you for the replies.
It's a hard top TC not a pop up.
The owner is trying to find a bracket that he doesn't have to drill or add additional metal to but it doesn't seem like they exist for a dually. The Atwood site is not very helpful and doesn't say how much space they add.
According to the second post he'll have to fabricate something...which is scary.
2011 Adventurer 910FBS truck camper,Torklift tie downs,Fastguns & Wobbl-stopprs
2012 Dodge 3500 DRW 6.7L CTD,4x4,LB,CC,auto,3.73 axle,General 17" on/off rd
2008 Lund 1825 Explorer Sport,115 Merc,9.9 kicker,Torklift Super Hitch,42" Supertruss
USAF ret E-9&E-7