Definitely, a Pacer 500 which others have said was the replacement for the Silver Streak. This was the first bike to be produced by Diamond Back in Taiwan, after their move from Koizumi in Japan. The bike was a flop due to the name. It was rapidly rebranded with different decals in a few different guises, like Viper, Super Viper and Silver Streak over the course of 1984. This has been the cause of much confusion as there are many bikes, all identical frames, that people believe to be different models.