For a gallery of photos of this 67 Ferrari 412 P http://flaviendachet.blogspot.com/2010/10/67-ferrari-412-p.html
According to http://www.dexigner.com/product/news-g12107.html Dean owned one of these 1967 Ferrari 412P on exhibit at the Cincinnati Art Museum. This is collborated by a commercial on the HDtht channel, which gives the following info: raced by the Belgium team Ecurie Francorchamps, owned by Harry Yeaggy, and was featured in the Cincinnati Art Museum from Nov 2007 to Jan 2008 http://www.designtaxi.com/news.php?id=13507
Also, just found a collaboration http://www.austin360.com/blogs/content/oh/story/entertainment/events/2007/12/26/fe122707calendar.html
Exhibit of the 1967 412P Ferrari. On loan from Harry Yeaggy, car has been owned by Hollywood movie mogul, John Calley and actor James Coburn, as well as Dean Martin Jr. and Cincinnati's own Carl Lindner. Through Jan. 6. Cincinnati Art Museum.
http://www.cincinnatiartmuseum.org/Absolutenm/templates/ArtTempExhibitions.aspx?articleid=590&zoneid=78
For a gallery of photos of this 67 Ferrari 412 P http://flaviendachet.blogspot.com/2010/10/67-ferrari-412-p.html 
the Facel Vega I posted about last year http://justacarguy.blogspot.com/2009/03/dean-martin-and-facel-vega.html
a 1976 Stutz Blackhawk 
from what I could learn in searching the internet, Dean owned this Ghis L 6.4, a 1967 De Tomaso Mangusta Fantuzzi Targa, a 1966 Ferrari 330 GTC, and a 1972 Cadillac station wagon: http://justacarguy.blogspot.com/2009/03/1972-cadillac-station-wagon-1-of-2-made.html 
