I bought a rebuilt 318 from a big engine rebuilder here in jax the other day,paid for the moter & core ($500) when i took the old core to them they would not give my core $ back until they checked my old block.My question is ,is this standard practice ??? They say if somthing is bad i get charged for that part. this seems like b.s to me . IF the old engine was`nt bad i would not need a new engine is my thinking. any comments greatly apprieciated