Welcome to the site! I like your gas tank.

As mentioned without modding, the pins, hexes, and nuts should work. You msy get lucky on a dog bone.
I would not if its an rs4. A556 front axles are getting scarce. A557 rear is one or two 30.xx+ alot of the 6x52 dog bones are gone. I just picked up 6x47 in hopes of getting it to work.
Not trying to keep you from doung it, just make sure you have spares before so its not all the work and have damaged unreplaceable parts on the end.
I'm up for a good project. Are you looking at hard to get parts Tamiya or a challenge build? Regaurdless, a 3d printer may become your best friend.