I don't know if Amsoil has changed their design,but I initially used an Amsoil drop in. Mine had a gap of probably a 1/8" around it's mounting surface. My Amsoil rep said Amsoil was aware of it and offered me a refund but I've still got it. My rep told me he'd run one forever in Utah,and the intake hose passed the "white glove'" test. The sealing surface gets compressed by the upper box thus providing the security. However,every other filter I've run hugs that lower box better. Dodge has a new "double deep" design out now similiar to the 6. 7 one,but it lists for $41. 00 here locally.