Does anyone have a pinout of the firewall harness connector for the engine? I am trying to label all the wires before I tear the harness apart and make a standalone engine harness.

I pulled a complete working 1988 Astro LT 4.3L TBI w/ TH700-R4 transmission unsplit still wired up for a project car and would like to conquer the challenge of making it standalone without buying a $414 painless wiring harness. There's about 20 wires and I think deductive reasoning might get me through this.