For those interested I have both the DRAC and VSSB. These little boxes convert a 40 pulse tone ring into the signal to for the PCM or ECM, and speedo. The VSSB has more outputs than the DRAC. Power, ground, and sensor inputs are the same. The PCM 427 with VSSB uses the RWAL singal (anti-lock brake signal), 40 PPR signal, and 2000 PPM signal. The VSSB also converts the 40 pulse tone ring signal to 2000 PPM for the Speedo. The DRAC is missing the 2000 PPM signal to PCM but because i am using a cable driven speedo i can use the 2000 PPM signal from the DRAC as the signal into the PCM by relocating one wire. With the correct diagrams and much research they can be used interchangebly.
As a side note from another question long ago in this thread the VATS pin is pin B7. There is no wire in that location but it is +5 volts and when pulled low at 30Hz the PCM will allow engine start. So enable VATS and use pin B7. I have tested it and activtly using it in my conversion.