GMC / Chevy Starter Switch

[DesertSpider]

I have a 90 gm 350 that I am rewiring. The original harness had more connections than my aftermarket kit. Can anyone give recommendations for a good video or wiring schematic for the starter switch? The best I have found so far is the attached image. It says 77 which is still a 3rd gen but can I use this schematic for a 90 350? If it is ok. What does the orange writer come from? Thanks in advance!

 

[DaveB]

On the 77 schematic that I have the orange wire is labeled as Ignition 3. It goes through the firewall connector and out to a connector that appears to be for the oil pressure sensor.

 

[mbryson]

I have an ‘89 Suburban TBI 350 harness in my “Jeep” and am in Bountiful if you want to look at an original harness