The first 400GT, commonly referred to as simply the 400GT or 400GT Interim, was essentially the older 350GT featuring an enlarged, 3929 cc (240 c.i.) V12 engine, with a power output of 320 bhp (239 kW). Twenty-three of these cars were built, with three featuring aluminium bodywork.
The second 400GT, commonly known as the 400GT 2+2, had a different roofline, and minor sheetmetal changes compared to the 350GT and first 400GT. It was first presented at the 1966 Geneva Auto Show. The larger body shape enabled the +2 seating to be installed in the rear, where the 350GT only had room for luggage or +1 seating. The bodywork was designed by Carrozzeria Touring. The 400GT 2+2 also had a Lamborghini designed gearbox, with Porsche style synchromesh on all gears, which greatly improved the drivetrain. When leaving the factory the 400 GT originally fitted Pirelli Cinturato 205VR15 tyres (CN72).
A total of 23 units of 400GT Interim and 224 units of the 400GT 2+2 were built from 1966 to 1968, when it was replaced with the Islero.
Source: Wikipedia (original)