A worthy successor to the 365 California, the high price did not prevent it from enjoying a certain sales success, particularly in the United States, where it is still considered a cult car. Almost a year after the introduction of the 365 GTB4, a spider version, the 365 GTS/4, was announced at the 1969 Frankfurt Salon, which was visually identical from the waist down, only the folding canvas roof and boot profile being different. The spider version proved to be extremely popular, particularly in the American market, and from the time of its introduction accounted for about ten per cent of 365 GTB4 model sales. Since then a number of berlinettas have had the roof cut off to be converted into the spider variant, this vogue being particularly popular in the late eighties as the price of original examples soared. Both variants of the model were produced up until 1973, which by the standards of previous models was a lengthy run, during which time a total of 122 spider examples were built in the chassis number range 14365 to 17073.
At the 1969 Paris Salon a one-off “Speciale” coupé was shown by Pininfarina on chassis number 12925, which featured a stainless steel roll hoop, and a zip out rear window, although the roof section was a fixed panel. It also featured a longer tail section and the rear quarter bumpers wrapped around the body sides. A few other special bodies were produced on existing cars by Michelotti, under the instructions of NART supreme Luigi Chinetti and/or his son Luigi Chinetti Jnr.

The bodies were mounted on a 2400mm wheelbase chassis that had factory reference numbers 605, all were numbered in the odd chassis number road car sequence. The construction was along the same basic lines as the others of the period, with large section oval main tubes, cross bracing, and sub structures to support the body and ancillary equipment. The model was available in either right or left hand drive form.

The standard road wheels were five alloy spoke “star” pattern, with a knock off spinner on a Rudge hub, although the American, and certain other market cars, had a large central nut due to legislative requirements. The option of Borrani wire wheels was available throughout the production period.

The engine was the same V12 unit used in the 365 GTB4, with factory type reference 251, of 4390cc capacity, with a bore and stroke of 81mm x 71mm, with dry sump lubrication. It was fitted with a bank of six twin choke Weber 40 DCN20 or 21 carburettors, those of the USA market cars carrying the suffix “A”, with a twin coil and rear of engine mounted distributors ignition system, with an electronic system fitted to USA market versions, to produce a claimed 352bhp.

The USA market cars were also fitted with a number of devices to control exhaust gas emission, including a fast idle device, and an exhaust manifold air injection system. The engine drove through a flywheel mounted clutch, via a shaft running at engine speed in a torque tube, to a five speed transaxle mounted in a similar way to that of the 275 GTB4 model, and then by drive shafts to the independently suspended rear wheels, with wishbones, coil springs and hydraulic shock absorbers to each wheel.