Positive Update: I started the car last night in garage, and noticed very sharp/hard engagement going from "P" to "R" or "D", a condition new to the car. Removed the SC shift-kit and cleaned up batt ground. Took her out for a short drive this morning and noted right off the jarring engagements were gone, and shifts were extremely soft, as I remember my '93 shifted. No repetition of the P0748 code either. Looks like QC install is next!!
Thanks to everyone for their assistance!!
Glenn