Ive done several . ( not going to Carlisle btw ) in both ac and non ac style.

IMO the hardest part on the non ac boxes regardless of body style box you are doing is reinstalling the riveted brackets IF you remove them to be replated. ( most dont btw )

Ive found out most clients don't care if the brackets get replated or not. So I quit doing them unless client wants it. If they do it adds a couple hundred $ to the costs due to labor involved

AC boxes are A LOT more complicated to do, regardless of body style.