Holden Trimatic / TH180 vacuum modulator (new /adjustable made in the USA) is known for leaking internally or allowing oil up to the manifold. Adjustable range: 66-75 kpa Do not use the factory gasket as they create leaks! (25 years experience in building transmissions) Use 3j permatex (form a gasket the brown-gooey stuff) just on the thread. suit 4cyl, 6cyl, & V8