Hi Salvador, thank you for reaching out. You need to wait for your order to arrive. Then, simply mail the core back using the exact same box your replacement arrived in with your original receipt within 60 days. You must use the exact same box in which your replacement part was received. For more information, click this link: https://www.carparts.com/customer/returnpolicy You can use this link to order the part and take advantage of our low price for this item: https://www.carparts.com/alternator/quality-built/mpa8285612?can=CPAP3648_CSQA_20240211 Should you need further assistance, feel free to call us at 1-866-529-0412. I hope this helps. Happy shopping.