sometimes...
de hole in the firewall...to get long stiff rods into the fuse
nice if the tank and engine was'nt installed first.

you can also use strings as a pull line to pull the rods thourgh the rear exit
of the fuselage.
use weight..screws, needle or whatever to help run the string.
same method for dual aileron servos.
some ARF have guide tubes...some don't..

there's also rubber gromets and eyelets use to mount the servos.
this help isolate vibrations to the servos.
the flange side of the eyelet gose between the servo and mounting surface.