I like to use carpet remnant scraps (usually free at carpet stores) for heavy parts. Wrap the part tightly like a burrito, fuzzy side in. Use 3.00" wide fiberglass rienforced strapping tape or better yet, steel or plastic strapping bands to secure it. After tightly wrapped LABEL BOTH of them individually, then strap or tape them together tightly, then place in a snug fitting HD cardboard box that is well taped and solid, you should feel zero slop from them shifting inside. Regardless of who you ship with they'll probably arive in good shape. I ship intake manifolds this way as well.