[edNorth]

Mikael, I know of this. And have Norm for plates. Your text applied to many Ju aircraft, incl. Ju 52/3m, Ju 88 just did not, and different types used. Type shown is Abnahme Schild. Other below cockpit usually had four fields (not shown because of copyright issues). But as the five factories did not always use same location, the "general" location is given in #2. Besides NEVER (proofable) found foto of mainplate Ju 88 below cockpit, on the side, like Ju 52 had. But the maybe I have been lied to 50 times.

Looking in my HD there appears some Ju 88 had main plate in under nose window position,

found one "three field" plate on one D-1, thats same as first position as Chris Goss suggested.
Plate of 0119 was under fuselage, near Bola door. I have picture or original but can not post, due copyright.
Problem: each time fuselage bottom was painted, it dissapeared under paint.

Found one Ju 88 C-6 with plate on cockpit side, near bottom, directly under pilot seat.

So location of plate, it appears more positions were used than above in #2.