When I got my 215's I kept the originals. The guy and the pump shop charged me something like $50 core charge. (I still can't find where I put them). I don't think he charge me a core charge on the 300's. I'm glad I saved them, cause I took them in and got them cleaned and tested and (as soon as I get my truick running again)I'm going to put them back in. Those 300's just like that $4. 15 @ gallon fuel too much.