Those were the days ... and your right Ed, Radio shack did indeed have the right adapter ... I know because I bought one there years ago, its still around here somewhere !
In the meantime this one here should suit your needs.
https://www.mypilotstore.com/mypilotstore/sep/11067
Plug your headset into the inline jack on the lower left of this photo and the curly cord jack into your TV.
Depending on headset impedance you may need a readily available cheap pre-amp between the TV and the curly cord jack.
Good luck.