According to the colored part list (Bauausführungs-Übersicht) attached on one of the earlier pages the nacelle tank system could be retrofitted to A-2 and A-0.
EDIT - Attached to this post:
http://forum.12oclockhigh.net/showpo...&postcount=140
Notice the parts with Asterix in the section "Bedien- und Leitungsanlage"