HP 11713A attenuator driver modification for 15V and 5V

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Hello,
A lot of HP/Agilent/Keysight attenuators operate now with 15V  or 5V instead of the traditional 24V supplied by the 11713A. Is there a HXX option for these supply levels or did anybody modify the 11713A to accomodate these various command levels ? Thank you.