Going only by the James D. Mason book, Combat Handgun Shooting (1976), early Hogue stocks were two piece, with several styles unlike current production, but ... Patrick ought to know.

I would have guessed Hurst, but ... OIF2 ought to know.

I do know that I like them!!

What was Hogue's Del Rey/Ray connection?

Tangentially - Mason lists a couple of grip makers I don't recognize. No pictures, either.
J.M. Evans, San Jose, CA and John W. Womack, Shrevemont, LA.

Funny that Mason features Hogue grips heavily but doesn't even mention Farrant or Hurst.