yeah only difference btw 240sx and 300zxt TB is 5mm. stock 280z is 50mm with 2 inch mouth, 300zxt/300zx is 55mm with 2 3/4 mouth, and I think 240sx is 60mm with 2 3/4 mouth too. I'm using 300zxt 55mm TB with mouth hone to 70mm (ram air baby!). I'm looking for faster air flow rather than large mass of air for better response that's why I'm not using 240sx TB. This swap is not easy as just bolt on since you have to deal with AFM, TPS, and vacuum advance. (those make your car run!)