55 Steering gear box, rebuild customers unit, 2 tooth vs 3 tooth: 55 had 2 tooth 57 had 3 tooth 56 can be either, but you may be able to tell by looking at the dome on top. If the dome is about 5/8" tall, it is 2 tooth. If it is less than that (flatter), it is 3 tooth.,extra charge for bad gearsDUE TO THE SHORTAGE OF CORES YOU ARE REQUIRED TO SEND YOUR OLD CORE TO US FIRST. . All gear box cores must be inspected by the rebuilder before a rebuilt unit will be sent. Send to: Thunderbird Headquarters 4020 Pike Lane Concord CA 94520

WARNING This product can expose you to chemicals including cadmium which is known to the State of California to cause cancer, birth defects or other reproductive harm. for more information, visit: www.p65warnings.ca.gov.