Can a DBW auto harness be converted for a 5-speed swap (4.8 into an NV3500 truck)?

Here is what the documentation says. Each point links to its source; details depend on your exact computer, harness and transmission.

Transmission control

• American Autowire's update instructions state that with a factory manual transmission the purple #5 and #6 wires are connected together if no neutral-safety switch is used, where #5 is the ignition-switch start feed and #6 is the output to the starter solenoid. (Api)
• Painless's 60250 instructions state that with a standard (manual) transmission the neutral-safety wire goes to a clutch-pedal-position switch that grounds when the clutch is depressed. (Images)

Throttle (drive-by-wire)

• 0411, 242; T56/TR6060, T5, TH350, TH400, Powerglide, 700R4, 200-4R; 1999-2007: PSI's Gen III 24x DBW controller kit for manual and non-electronic transmissions covers T56/TR6060 manuals and TH350, TH400, Powerglide, 700R4, and 200-4R automatics, and includes the same DBW pedal (ACC-1049), TAC module (ACC-1011), TAC harness (HAR-1022-C10), brake switch (KIT-1002), and tuned PCM (PCM-1005) as the automatic kit. (PSI Conversion)

Harness and power

• E38 ECM; Aeroflow AF49-1506; 58x LS3/LSX; DBW; T56 or non-electronic automatic; 2006+: Orange clutch wire goes to ground with the clutch depressed. (Aeroflow Performance)

Confirm against the instructions for your exact parts before wiring. More: Transmission control in our tuning guide.