The S.E.F.A.C. corporation (Societa Esercisio Fabriche Automobili e Corse) was founded the 23rd of may 1960 by Enzo Ferrari and Michel Paul-Cavallier, who was made its C.E.O. He was an important french industrial (foundries of Pont-a-Mousson) with a passion for sports and racing cars. He would regularly go to Maranello for meetings with Enzo Ferrari and his engineers to finalized different projects, like a car based on the engine and the bodywork of 250 GT.

This prototype of the 275 GT/B #05161 GT on the chassis and powertrain of the 250 GT and the aluminum body will be studied in the wind tunnel and will become the first prototype 275 GT/B delivered 03/20/1963. A real rear ressemblance with the 250 Lusso and the 250 LM #05149 (only 5 cars apart), the 250 GTO 1964 will come out a year later
In 1963, 2 cars will come out of Maranello with a similar body line : the 250 LM #5149 and the 275 GT/B #5161 GT.

Rear view of the 275 GTB #05161 GT.

Rear view of the 250 LM #05149 GT.

The study of those 2 prototypes will not be in vain, since Ferrari will use the same roof on the rarissimes and last GTO of 1964

250 GTO 64'.

In 1964, Ferrari will built the second prototype 275 GTB #06003 GT short nose, to come back by the end of the year to the long nose of the first GTO of 1962

The 275 GTB #06003 In the Monte-Carlo Rally 1966.

In spring of 1963, during testing at Fiorano, the #05161 GT will crash and subsequently given to Michel Paul-Cavallier. After his death, it will be sold by the garage of Hughes Hazar of Nancy to the Colonel Dick Mitchell of the USAF base of Rosieres-en-Haye.
Gone to the United States, in the mid sixties it will be made into a cabriolet and will stay in a garage in Sacramento CA. In the nineties, it will go back to Europe to finally be restored to its original configuration.
Please see this post about the 275 on the FerrariChat forum.

Michel Paul-Cavallier, unfortunately, will not see the projects coming to fruction with the fabrication of four 275 GTB Speciale competition, leighter and faster, numbers #06701 / #06885 / #07185 and #08249.

The 275 GTB #06701 Competizione Speciale 1964.	The 275 GTB #06885 Competizione Speciale 1965.	The 275 GTB #07185 Competizione Speciale 1965 "Nez Long".	The 275 GTB #08249 Competizione Speciale 1966.
The #06701	The #06885	The #07185	The #08249

They will be Special Competition. "Competition" in quotes because F.I.A. and C.S.I. refused cars more than 5% less weight, which was a big problem because the standards often changed. Nonetheless these four special 275 GTB were built for racing in the continuity of the 250 GTO, each with different patterns, but with common :
    - weighing 150 to 200 kg less than the original model
    - few millimeters alluminium bodywork
    - engine type LM 250 213 ribbed four attachment points
Shortly after the 4th Special 275 GTB Competizione, emerge twelve 275 GTB/C on the 9000 series, with the four Special Competition, they are the only car to have a 250 LM engine type 213.