I believe
all Nash units for that era are wood, for Arctic Fox (of that era) look for Silver Fox edition, those are Aluminum framed, the others are wood.
That all being said, what matters more then if a rig a framed of wood or aluminum is workmanship. The one of the best companies will build with wood, another with aluminum, while the same can be said that the worst made rigs could be built with either
2008 F350SD V10 with an 2012 Arctic Fox 29-5E
When someone tells you to buy the same rig they own, listen, they might be right. When they tell you to buy a different rig then they own, really pay attention, they probably know something you don't.