Are inner fenders necessary when swapping???

[WRMZ71]

OK I'm changing my truck to A/C and pretty much am doing a frame off. I have all brand new body parts for the front end except the inner fenders. What I'm really wondering is if these are necessary to swap out when changing from non a/c to a/c. I'm pretty sure when you order them you have to let them know if you have a/c or not. If there is a difference what is it? does anybody know? Thanks for the help folks.