E.g. the C-series, which, as a nightfighter, was equipped with 3 forward firing 20mm, 3 forward firing 7,92mm as well as a twin 7,92mm at the back of the rear cockpit plus later on another two upward firing 20mm ("Schräge Musik").
The C-series was the dayfighter.
Ju-88 variants:
Day-fighters/Destroyers:
C2 - 2x MG17 defensive, 1x MG FF + 3x MG17 forward
C4 - 3x MG17 defensive, 3x MG FF + 3x MG17 forward
C5 - 2x MG17 defensive, 1x MG 151/20 + 5x MG17 forward
C6 - MG131 or MG15 cockpit, 3x MG FF + 3x MG17 forward
C7 - MG131 or MG15 cockpit, 2x MG FF + 3x MG17 forward
Night-fighters:
G - MG131 or MG15 cockpit, 4x MG151/20 forward, 2x MG151/20 upward
R - 1x MG FF + 3x MG17 + 2x MG151/20 forward
Long-range fighter:
H - MG131 or MG15 cockpit, 6x MG151/20 forward
Anti-tank version:
P1 - 1x PaK 40 (75mm), 1x MG81 ranging, 4x MG81 forward
P2 - 2x FlaK 38 (37mm), 1x MG81 ranging, 4x MG81 forward
MG15, MG17, MG81 : 7.92mm
MG131 : 13mm
MG FF, MG151/20 : 20mm (different rounds)
Optional "Schräge Musik" dorsal upward-firing twin MG151/20 in C6/C7/G versions, standard in G6a onwards. Equipment may vary, e.g. replacement of MG15 by MG81.