There is no special cap for the recovery system. All rad caps will release at the set pressure and all have the vacum release also. Its just that when it has the recovery tank the coolant released at the pressure setting will go into the tank instead of on the ground. And then when the vacum release valve opens with the recovery it pulls the coolant back into the rad which the older cars without the recovery tank cant do that since the coolant went on the ground. But the caps all worked the same other then different pressure settings which for every lb of pressure on the coolant raises the boiling point 3 degrees. Ron