Dont except this bullshit, you know that the gearbox is different and so does your "so called mechanic".
He noticed the celica writting on the gearbox no-ing full well that your car is a supra and then he sends you to HIS USUAL GEARBOX PEOPLE.
Stand up and correct this shit, and get a new mechanic, the one you have is not looking out for your best interests, he is a joke, and so are the gearbox people.