just put in a new posi what gear oil?

if its a locker there are no clutches just straight teeth right? that is a locker and will make loud noises when you turn cause the teeth will slam together while turning. and my dads friend had problems with synthetic gear oil in mopar cone type rears so. i used lakewood bfl yellow label gear oil in my 8 1/4 with a clutch sure-grip. i dont know if theres a special gear oil needed. if you have "instructions" see if it says anything about a special gear oil needed.