i need to swap out a new diff because i grenaded my spider gears and destroyed my carrier. i found another diff with a gear on it but dont know how to read the numbers on the ring gear. mine says 2 GM 3988518 11 41 4 87. i dont know what the other one has on it at the moment but can someone translate this number into a gear ratio? also, how could i get my ring gear off the diff? i have tried a lot of force but the bolts wont budge!