What parts or kits did Beech offer, to install the external power receptacle?
Search strings: power plug, power outlet, ground power, aerostart, haynes
There were three kits that Beech used to install the external power plug receptacle. In order of succession, they were PN 35-300002, superseded by PN 35-676-1, which was again superseded by PN 23-3007-1 or -3. All of these kits contained the primary part, AeroStart ground power receptacle PN HAS-62, made by Haynes Corporation. None of these kits is currently available from any known source.