How do those ebay ~$200 ebay aluminum 3 core radiators compare to a good stock 1200 radiator?

A good stock 1200 radiator was marginal when new. The GX came with a 3-row unit which kept cool at high RPMs and hot days, as does the aluminum 3-row units. But a new N14 or jetta unit cools even better and costs less.

I bought an eBay one from asi in Melbourne for $185 posted and highly recommend. My standard radiator couldn't keep my a15 cool now it's great.

Yeah, they started selling those about 6-12 months after I bought a civic one with the same core size. Would have been much less messing around. I had to make up brackets and a curly bit of pipe to mount and plumb. Oh well, next time....

anyone with datsun 1200 user manual in english kindly foward to lkivinda@yahoo.com

did you check the thermostat..? when the datsun get that hot again feel the water inlet and outlet pipe on the radiator(top and botom pipe ) if there is a big diference between them ,your thermostat might be broken .. .. take the thermostat out and put it in a pot with boiling water ... if it open its stil fine...

The moral of the story with the factory gauge is to ignore or unplug it and get an actual gauge. I use an "Engine Gaurdian" thermocouple gauge on all my cars.
They read accurately even if water is lost - the standard type has to be immersed in water to read accurately, and even then you have NFI what the temperature actually is. Withthe thermocouple digital gauge you know down to the degree what the actual temperature is.
They have 2 programmable alarm levels. Let's face it - no-one watches their gauge all the time, and the first thing most people know about their car overheating is when they see or smell the steam. With the audible alarm you don't have to worry about it.