They aren’t conveniently interchangeable since the two mounting bolts are even more apart around the Blacktop trumpets. Please see “Throttle bodies” for more information. Also the opening from the Blacktop inlet ports are about four to 5mm wider at their entrance around the Silvertop providing a larger cross sectional location. https://4ageenginesale59369.articlesblogger.com/54932767/everything-about-toyota-4age-for-sale