Yeah, then you want the GM pigtail. I actually think I have one laying around, it came on a wire harness I bought years ago.
Just for reference sake for anyone that finds this through search, you should be able to use any 3SGTE knock sensor up to at least 99. There are at least 2 different part numbers. The 90/91 and 92/93 have different numbers. IIRC the 94 - 99 were the same as the 92/93. The threaded part that threads into the engine were the same but the connectors were different.
Also, that year breakdown is for the Celica. The MR2 I believe is 90 - 92 and 93 - 95 in the US and 90 - 92, 93, and 94 - 99 for the rest of the world?
I don't know why Toyota used different sensors. Either they just ended up with different connectors, or the specific frequency they listen for is different. Not sure which.
Point being, the newer 3SGTEs shared sensors with some other engines, like I believe the 1 and 3MZFE. So it should be a whole lot easier to find a sensor and connector for those.