Speedo

Hi, eyeing up a 92 jdm model. One thing I note is that the speedo runs to 300kmh. Initial gradiation is, after 0, 60kmh. Thereafter gradiation is 40kmh increments (100 140 180 etc) to conclude at 300. I take it this is non original or is it? as best I can figure true jdm runs to 180 and the Canadian 300 speedo runs in 40k increments to 280, true? So is the one I'm interested in home made or are there oem ones out there that match my description, and any reason why such an oem part would get replaced