Any Reason Why A 6.2L Catback WON'T Fit On A 5.3L?

[Mad Maxx]

I noticed that Magnaflow's Exhaust for the 6.2L Trucks is a 3.5" System, whereas their Systems for 5.3L Trucks are 3".

Is there any reason why the 6.2L System wouldn't fit on a 5.3L? Are the Flanges different at the Cat Connection?

I know on the older 6.0L & 5.3L, the Header / Cat piping layout was totally different between the 2 and would take work to get it to fit...but looking at the Part Diagrams for the '15 Trucks, they look identical, they just have different Part Numbers.

 

[SRTH8R]

My guess is the flange is differant. 6.2 has 3.5 inch from the factory. Steps down a little after the muffler.