Here's where it goes.

Sec. 45.11

General.

(a) Aircraft and aircraft engines. Aircraft covered under Sec. 21.182 of
this chapter must be identified, and each person who manufactures an
aircraft engine under a type or production certificate shall identify that
engine, by means of a fireproof plate that has the information specified in
Sec. 45.13 of this part marked on it by etching, stamping, engraving, or
other approved method of fireproof marking. The identification plate for
aircraft must be secured in such a manner that it will not likely be defaced
or removed during normal service, or lost or destroyed in an accident.
Except as provided in paragraphs (c) and (d) of this section, the aircraft
identification plate must be secured to the aircraft fuselage exterior so
that it is legible to a person on the ground, and must be either adjacent to
and aft of the rear-most entrance door or on the fuselage surface near the
tail surfaces.