AE warrants their products to be free from defects in material or workmanship for 12 months or 12,000 miles, whichever occurs first. If all lifters are being replaced, you can use either of the following kits: 270866 for 5-Cyl.(Contains 20-pcs.) or 270865 for 6-Cyl. (Contains 24-pcs.) Please beware that "Lifter Noise" may be caused by insufficient oil pressure that may be caused by leaking O-rings in the Oil Sump area. If replacement of these O-rings is necessary please use Part Number 8648358 O-Ring Kit.