Buzzr's listings show episode 149 for Truth '90. Marshall Akers' site shows the following three subjects during that episode, which has a panel of Orson Bean, Dana Hill, David Niven Jr., and Kitty Carlisle
Harold Wilkins - Game show fan and date for Kitty Carlisle
Eddie Benales - Former gang member, author: "From Gangs To Grace"
Mark Wayland - Head bump doctor/Owner of traffic school
I have to assume Barker or Price may have some tangential connection to the first subject (at least unless Barker was in a gang, had a concussion, or needed to clear a parking ticket). Either that or Buzzr just really needed to fill a 30 minute hole that day and went with Truth (tangent about this below the line)
And as far as I know Barker never did a walk-on (and NBC probably wouldn't be in a massive hurry to promote the star of their competitor's top daytime game)
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(tangent: honestly I am shocked that they've never put the 1980, 1990, or 2000 reboots on the regular schedule - the 1990 version in particular feels like it'd be a great daily fixture for the channel, or 2000 for something more "contemporary", meanwhile 1980 has a really fascinating list of guests)