With the exception of the 1993 NX1600 model, all Nissans in 1993 converted to an electronic speed sensor. It has been proven that the cable speed sensor and electronic speed sensor are different lengths, and therefore cannot be interchanged within transmissions. So, get a transmission that is post 1993. This sucks for you post '93 owners because you cannot use the coveted Pulsar NX and NX1600 transmissions with the best gear ratio .
That's because there was already an electronic speed sensor in your '93 transmission. You can't use anything pre-1993 on the later model B13s and B14s. Or, perhaps, what did you do different that everyone else who has tried has failed miserably at?