All OEM radiators are plastic capped, yours is a generic aftermarket radiator with metal caps. I know this because I had to replace the OEM plastic one and decided I wanted to go with a metal radiator. ArkLaTexSC, if you have that metal one, it's also a generic brand aftermarket radiator, not OEM. The OEM part also has the word Toyota along with the part number stamped on it right at the top near the upper hose as seen in the pic of the red one.
Here's an eBay link to the metal aftermarket, brand is CSF.