There are six examples of the Miura SV/J known to be built by the factory while the Miura was still in production, one was built new (chassis #5090) and five were converted from existing SVs (chassis #4934, #4860, #4892, #4990 & #5084)
One of these cars, chassis #4934, was built for the Shah of Iran Mohammad Reza Pahlavi. The Shah stored this car under armed guard with another SV in Royal Palace in Tehran. After he fled the country during the Iranian Revolution, his cars were seized by the Iranian government. The SV/J was sold into Dubai in 1995. In 1997 this car was sold in a Brooks auction to Nicolas Cage, at US$490,000, becoming the model's highest ever price at auction. Cage sold the car in 2002. Higher prices have been reached several times since then, including by SVJ #4892 selling for over $1.9M.
An eighth SV/J was built at the Lamborghini factory between 1983 and 1987 from an unused Miura S chassis. This was made for Jean Claude Mimran, one of the Mimran brothers, the then owner of Lamborghini. Most experts do not recognize this as an "official" SVJ due to it being converted (albeit done by the factory) long after the Miura went out of production.
Source: Wikipedia (original)