Hi Brent,
IIRC, the Marque (small format) was from 1976 to 1980, five volumes with six issues each, totally 30. The large format "The Shelby American" started in 1981 with No. 31 with the numbering series continuing to this day.
Here is a link to all the SOA News letters from 1972 to 1975. There were only 21 issues. 1972 (5), 1973 (6), 1974 (6) and 1975 (4). There were two issues identified as December 1974. The December 1974 black and white version (cover image with COBRA with No. 2 on hood) was actually December 1973. The correct December 1974 colored version has six cars on cover.
http://www.saacforum.com/index.php?topic=660.msg4443#msg4443Hope that helps.
Cory