anbody ever hear of an outfit called dynagroove records?

It was a recording process that RCA introduced many moons ago!
https://en.wikipedia.org/wiki/Dynagroove

they are record dealers

It’s an odd choice of names since Dynagrooves were a few steps down ⬇️ generally speaking from their predecessor, Shaded Dog 🐕 Living Stereos. Some were really good sounding, though.

Yogiboy and geoffkait are correct.  I've sometimes referred to these records as "Dynaflaps" because they were so thin.  But some were very good sounding - like ARL 2-0731 - Schubert Piano Trios with Rubenstein, Szeryng and Fournier.  Still play that one once or twice a year.