Neither the Phoenix that I have or the Fluidyne have staggered tubes like your graphic. The Phoenix is 4" thick and the tubes have a thicker wall than the Fluidyne but the best i can tell is that they both have five rows.
John
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.