I'm not going to name the prison but he is in P.A and in witsec because of his past cooperation from the early 90's. Him being in witsec has absolutely nothing to do with his arizona case in which he did NOT cooperate. They basically wanted him.
Truth is, Gravano wanted nothing to do with drugs or illegal activity, he thought he was going to make money in the pool business. In fact, when he found out his son and daughters boy friend were involved with Ecstacy, he was against it and wanted them to focus on construction. In the end, he kind of served as an advisor and took control of the money part and took most of the wrap to protect his son. Im not sticking up for the guy, just stating facts. Take that with whichever grain of salt you choose.