Alright so I just put in a new (and by new I mean used) LSD in my 87 na rx7. I made sure to torque everything down right and put in new diff oil with lsd additive. But when i drive it, it makes this annoying pulsating noise that gets higher pitched and faster as I speed up (naturally). It is loudest around 40mph and gets louder when I decelerate and is especially loud when i just coast in neutral. I really hope its not this new diff, any ideas?