Could not find the pictures I have of a really nice original 68 X code (they are somewhere in the 40,000 ) but here is an X code with the decal locations notated
#1- Battery inspection decal (filled out) Correct decal currently is not widely available
#2- Engine ID tag (paper) Reproduction is plastic - remember to tear the ends on a tape dispenser to reproduce the original looking ends (on the front surface of the passenger side head
#3- (Radiator shroud) If you car has one NO - CAUTION decal was originally supplied
#4- Service decal
#5- Emissions decal applied below the breather location above the gasjet lip of the valve cover
#6- Air filter - service replacement parts decal - Original would include the part number for the air filter in small aerial print along the lower edge (cheap reproductions do not include this detail)
#7- Engine size/displacement. Small orange with white "flags" on ends
#8- May or may not have the tin foil with red print brake fluid warning label since we are discussing spring built cars
No decal on voltage regulator (was ink stamped C8AF for standard C8TF for HD charging)
No decal on coil. Original was ink printed. Reproduction decal is normally (due to date) made for a 70 car - but again no decal
Hope this helps