MRL: You're right, the same final-generation p-mount styli keep coming up again and again renamed as Studio Reference, VectorScan, Precision Technology, Digital Research, Transducer Research, Precept,Trackmaster... and on and on and on. Many clones are simply labeled Audio-Technica, with unexplained prefixes that indicate Gott knows what.
I believe the original series from which all these clones sprang is the AT3#1series, with the Linear Contact model being the AT331LP. But there's also an AT113LC. Plus the AT3472LC. So you see, it's all so easy and simple...