BUFF Defence systems

I was flicking through my friends copy of Janes Aircraft recognition today. One thing which caught my eye, as I’d never heard of it before was that the B-52 has provision for a Stinger missle launcher in the tail, in place of the M61 cannon. Can this be done?? How effective would it be?… If it exists!!

Also how effective is the ECM suite on the BUFF, what could it defeat???

THANKS IN ADVANCE

LEE