This caliper is made up of Vintage 1965 cores, Casting No. 5465952 and 5465954. Order this product if you do not have Vintage cores to trade in. I have to charge more for this caliper due to the fact that these cores are extremely hard to find. If you already have the correct cores, and want to keep them, order the standard 4017, and select the R&R option, and let us rebuild your cores. I will accept Non Vintage cores for core credit. My Caliper Remanufacturing source has invested in automation tooling for this particular caliper, and can therefore offer it at a very agressive price. To avoid core charges, send old cores to our factory prior to shipment of remanufactured calipers, and select the Cores Returned Prior to Product Shipment option, under Core Charge drop down box.