The official document is . Because the KI 256 is legacy equipment (discontinued, though still supported for repair), you cannot find it on Honeywell’s main portal without a direct customer account.
The KI 256 is designed for standard instrument panel mounting. ki 256 installation manual
for the unit to reach operating speed before moving the aircraft. Critical Alignment Procedures The official document is
006-10565-00 Rev: C Applicability: KI 256 Electric Attitude Indicator (14V & 28V systems) though still supported for repair)