The stock 240SX fan is exactly 16 inches in diameter... from outer edge of 1 blade to the outer edge of the blade across from it. The 240SX fan clutch has 1 and 3/8 inch gap from each of the edges closes to each other... these are the holes that slip through the studs on the water pump. O|---|O Like in the diagram from the verticle line to the other verticle line on the inside of the holes (the verticle line is tangent with the inner edge). Im not sure if they're the same 'spread' as the 300ZX waterpump studs though. May take some customization...