Your PSI harness should have a speedo and tach output wires that is from your pcm
you can choose to run the speedo off the pcm leads (cleaner, less wires to route)or direct off your T56 speed sensor, just pay close attention, which "lead wire" that is required per the Autometer install instructions
If you choose direct off trans, you can "group" them in the same loom with your reverse lockout solenoid & backup light switch leads
Ron is correct also in setting your Autometer tach (switch through rear access hole) to " 4cyl"
The pcm reads off one side coil bank (4 coils)