Produced for weekly syndication 1974-1979
The classic word association game is most closely associated with Dick Clark, but Bill's weekly nighttime version enjoyed a healthy five-year run in the late seventies.  This version is not to be confused with the daily daytime series of the 1980s with the same name.

Since Bill's version of Pyramid was a weekly syndicated show, only thirty episodes were produced each year.  Those episodes were taped in a grand total of five workdays each season, typically spread out over a two month period depending on the availability of celebrity panelists.  (Fellow fan and researcher Daniel Benfield tells us the first season shot in the fall of 1974, and subsequent seasons shot in the spring.)  During the time Bill hosted this show in syndication, he hosted a variety of different games from Bob Stewart Productions on the network daytime schedule.  He also continued as a panelist (and occasional substitute host) on the syndicated To Tell The Truth.

The staging of Pyramid was quite different whenever Bill participated, in order to avoid showing his limp on camera.  As a player, Bill and his partner stayed at their podium after a win, rather than taking the customary dash to the Winner's Circle. Also, as a player, Bill and his celebrity opponent would already be seated during the opening introductions, rather than making the traditional walk-ons.

Bill and Peggy Cass are said to have helped Bob Stewart pitch the original version of The $10,000 Pyramid to CBS in 1973.

As the host of this version, Bill moved to the Winner's Circle during the final round, so that he was in place there at game's end.  When necessary, he also conducted tiebreakers from that position.  He did walk onto the set at the beginning, but from behind the main game pyramid so that he only had to take a step or two to reach his podium.

The $25,000 Pyramid became the last game show Bill Cullen hosted in New York City.  Starting with The Love Experts in 1978, all of Bill's shows were produced in California.
All 150 episodes still exist and are controlled by Viacom, the original syndicator.  These episodes are not among the various incarnations of Pyramid that have been seen on GSN: The Network for Games.  Circulating among traders are about twenty episodes (including two in which Dick Clark plays as a celebrity guest), most of which were recorded from a Long Island station that aired reruns in 1985. 
Watch part of a vintage episode:  

The $25,000 Pyramid page at Adam Nedeff's Bill Cullen's World
The more general Pyramid page on Wikipedia