I'll just add that the level of armour varied. For example, in September 1942 some A-3s were converted to high altitude fighters and received extra armour to the cabin, fuel tanks and fuselage guns.
"..der panzerung in kabinenbereich, der kraftstoffbehalter schutz und von der bewaffnung die rumpf MG17 ausgebaut worden."
Armour was added throughout the war. The standard A-8 'Jager' had 145.7 Kg of armours, the heavies (34.7 Kg and 43.5 Kg) being for the oil cooler and tank respectively. The heaviest 'Sturm-Jager' variant of the A-8/R2 carried a massive 337.3 Kg of armour.
Cheers
Steve