Flat Rate Round Trip shipping is our universal method of shipping via LTL Freight and UPS Small Package. It is based on 3 different zones: Northwest, West/Southwest/Central and East/Northeast each with their own price point for cylinder heads, short blocks, 4-cylinder long blocks and V6/V8 long blocks. Upon check out, you must select your zone from the drop down list and freight will be added to the total. FREIGHT IS NOT INCLUDED IN ENGINE PRICE. Round trip shipping is just like a round trip airline ticket, it covers the trip both ways so there is no need to pay a second freight charge when the core is ready to be returned. Simply give us a call or send us an email requesting a core return label and we will email it over as soon as possible.