Here are the new engine-mount fasteners. Grade 5 nuts and bolts, plus hardened flat washers for the Chevy side, and metric 10.2-grade hardware for the Jeep side. Lock washers are generally useless, while flat washers reduce friction and spread the force evenly. Find a hardware supplier who knows what he is talking about and has technical information on what he sells. Torque each bolt to specification based on fastener size and grade. Make sure you know whether it is a "wet" (oiled) or "dry" torque spec.