I'm having difficulty converting the coordinates of a WW2 radar installation to modern-day WGS84 (GPS) coordinates. The difficulty arises from the fact that New Zealand changed the reference datum in 1949 and again in 2000. The coordinates I have date from the period during WW2. The only indicators are a reference that states that the radar site was 1/2 mile west of the battery (227881.2 E, 671748.1 N). As to the unit of measure for Easting and Northing, I suspect it may be yards. So far, I have been unsuccessful in translating the coordinates. Coordinates for No. 1 gun of the battery are given as 187yd E, 14784yd N. I have tried using differential referencing, but that places me somewhere out to sea. I suspect two different maps were used in placing the coordinates of both locations. Any help you guys can give me would be greatly appreciated. WGS84 for No 1 gun is 36 45' 22" S 174 45' 59" E.