Let me correct above^
When toyota get their parts, they have specifications and the manufactures has to meet those specifications (part is labelled as TOYOTA or toyoda). The manufacturers can also make those and those are NOT 100% toyota standards (sold as Aisin/denso). AISIN and DENSO are owned by TOYOTA and many other manufacturers use AISIN and DENSO products in their cars (even BMW!).

Toyota OEM oil seals are made by NOK, you should see NOK embossed on to the lip or side oil seal. If I remember right, OEM drive belts are also Mitsuboshi.

Here is an example: I installed OEM toyota wheel bearing into a hilux axle and after the installation I could spin the dust shield smoothly. Another person installed a branded JAPANESE Wheel bearing (NSK, KOYO or NACHI: Not sure, but confirmed it was Japanese) on to his trucks axle. After his installation, the dust shield spun bit tightly.

I used Bando drive belts on my corolla and I have to adjust it after 300-400 miles, but recently used a mitsuboshi drive belt and even after 1100 mile road trip it didn't stretch a bit!