For my 305tbi to carbed 350 swap I've read that I don't need the harness from the passenger side but it connects to a few wires that go Into the firewall right behind the passenger side head as well as some on the drivers side. Is there an easy way to figure out what's needed?

 

Wiring going through the firewall near the heater hoses, is for the HVAC system. Should be totally separate from the "engine" (gauges, ignition, charging, starter, etc.), the "car" (lights etc.) and the "computer" harnesses.

 

Yup. The harness that goes through the firewall next to the heater box in a ~ 1" hole is for hvac. It should have 2 vacuum hoses in it and a couple of wires that run up to a relay and pressure switch, blower motor etc.

As I understand it the engine harness goes through the passenger side fender area through a rectangular hole. (my car was missing this, so I can't confirm this.)

 

Ok so I can just yank this out too. Just wanted to make sure since it connected with the passenger side Harness.