These replica long blocks are designed to bolt into your car in place of your real engine for test fitting parts. They include all of the necessary mounting holes with steel threaded inserts so you can mock up your new high performance parts. It uses steel inserts for all bolt holes, and all specifications are held to OEM tolerances. You can bolt any factory component or accessory to an engine and it will fit. Made from durable polyurethane foam and has steel inserts for easy mounting. Save time, money, and hassle when it comes time to install your next power plant. Combine with one of our LSx Swap Kits to make life so much easier for you.