So far, I've found a way to identify whether it has a MTK or NEC chipset by pictures, if available. The "-0x," "-3x," or "-9x" extensions are inaccurate indicators, only the letter after these, whether 'A' or 'Y' will be the true identification.
I've checked against my two MTK- and two NEC-based drives and these pictures are accurate. In the first picture, if the SATA connector has some metal content, then it's likely MTK, otherwise, NEC. In the second picture, the bottom case will also indicate which drive it is.
For picture reference, the MTK drive is iHAS524-32 A while NEC drive is iHAS424-98 Y.
Of course, for LO drives, it's just easy to look at the label. However, for rebadges like Asus, AOpen, Gear Head, Gigabyte, HP, Imation, Plextor, etc. where the label will indicate the actual drive model, the quickest way to differentiate is look at the SATA connector, assuming it's consistent.