Shipping heads

Get some heavy cardboard boxes and pack them separately if possible with extra cardboard for dunnage inside each one. Pack as tightly as possible and make sure you label them on every side.
I work for a transportation company and I have seen so many poorly packaged items it's ridiculous.
As RustyRatRod stated, you can use oversized boxes and cut them down as needed. I have shipped 2 sets of bucket seats in the last year or so in old refrigerator boxes. Both made it across the country unscathed.
Excellent advice in post #4 as well. I did something similar with a radiator that I shipped earlier this year.