"Laguna Seca didn't host a Trans-Am event until 1969 per Dave Friedman's book Trans-Am: The Pony Car Wars.  All six of the cars in the Jim Serniuk photo appear likely to be pre-1969 models. 

The 1969 (and 1970) Laguna Trans-Am fields included no Dodge Darts and no Mercury Cougars.  This event is apparently an SCCA Divisional A Sedan race event probably in 1968.  The leading and trailing Camaros appear to be of 1967-68 vintage with wideset headlights.  The light blue and white one could maybe be one driven by Dick Guldstrand or Tony Settember.  The yellow Dart might be one campaigned by Ron Grable before he drove for the AMC Javelin team in 1969.  The light colored Cougar might possibly be the one run by Dave Tatum (which he ran with Bill Pendleton at the 1967 Kent Trans-Am in black and red livery) in several 1968 Trans-Am races.  No idea on the white Porsche with stripes (Porsche 911s were made ineligible for Trans-Am after the 1969 season.) or the yellow #4 1966 Mustang. 

The blue and yellow Camaro at the rear of this pack appears to be in Penske Sunoco livery, but seems to have A Sedan lettering next to its driver side number roundel.  I'm going to have to dig through old issues of Competition Press to see if I can find reference to this event or photos of some of these cars."

(12-22-11)   From Neil Young:

"I'm quite sure the yellow Mustang is Don Peck. My sister and brother-in-law were crew. The car was built by Shelby."

(1-7-12)   From Mark Ellis:

"The yellow Cougar could also be Mark Waco."