Tires rubbing; is the suspension different in a Z71?

[belchfire]

OK, to make a long story short, I had a 2018 4WD, Crew Cab that got totaled.  I bought another 2018 as near like it as possible, right down to the color, but it's a Z71 (first 2018 was not).  Both have bone-stock suspension and the first one had Cooper Discoverer AT3 xlt (275/70/18).  So yesterday, I had those same tires mounted on the replacement truck and they're rubbing at full lock.  Those same tires on the same rims (a 5646, FWIW) didn't rub on the first truck.  Is the Z71 suspension different?

 

I bought both trucks used, but I know for a fact that neither truck had/has a lift kit or even a leveling kit.  I suppose it's possible that there were spacers behind the wheels on the first truck, but I never had them off and it's gone now so I can't check.  Other than spacers or the possibility that the Z71 has different suspension, what could cause rubbing in one truck when an identical setup in another truck doesn't rub?

[CamGTP]

The Z71 probably has different control arms. The trucks could come with steel control arms or aluminum arms.

 

Past that it's only the struts/shocks that are different.

[belchfire]

I don't see how the shocks could affect the rubbing, so I dismissed that in my mind, but you guys usually know more about these issues than I do.  However, I think I found it.  Had to get the wife's help.  Seems that the previous owner installed an extended mudflap and the outside edge of the tire is snagging the inside edge of the mudflap in a hard turn in reverse.  Strangely, it doesn't do it in forward on a hard turn, but then the tire isn't pulling the top of the mudflap down in forward; only reverse.  I may try trimming the top edge of the mudflap where it sticks out.  IIRC correctly the last 2018 had aluminum arms and this one does too.