You will not find Offy dual quad SBM intakes in the Jegs or Summit catalog. They are made-to-order and are sold only by Phethean Racing Products, AFAIK. They are calling them 360° Equa-Flow manifolds. These appear to be of dual plane design.
Chrysler: 273-318 V8 1966 and later Dual Quad Equa-Flow (5615) $516.15
Chrysler: 273-318 V8 1966 and later Dual Quad Hi-Rise ( 5698 ) $598.73
http://www.offyparts.com/images/offy_5615.JPG
