I have 2 very good sources for armour on the JU 87. " Knights of the Skies", by Michael C Fox , and " German Aircraft and Armament", a reprint of a WW II intelligence manual. I highly recommend both of these books if you are interested in the armour protection of WW II RAF and Luftwaffe aircraft.
Both give the following protection for Ju 87 s
Ju87b pilots seat 8mm , bulkhead for the rear gunner 8mm, coolant flaps 4mm, 2" bullet proof glass for the gunner
the Ju 87 D is much more extensive , frontal 8mm armour and 2" glass, pilots seat 10 mm head and 4-8mm back(seat), Dorsal 5mm(in roof), lateral 6mm(cockpit sides), ventral 5mm (floor), rear bulkhead 8mm, coolant flaps 3.5mm
Hohun, you are correct the BoB Ju 87b lacked the visable head armour plate. The pilot only gets a nice little amoured seat to curl up in.
Slaterat