2010 Toyota Tundra Stock Radio (without JBL)

Hope all is well! I am stuck on the backside of the radio. I have labeled 1-6 and was wondering what plugs in to each slot. I have purchased a radio from Amazon specifically for the model truck I have, and the harness connects to majority of all plugs. Issue is, I'm not sure which is for rear speakers. Can anyone tell me what 1-6 is used for? Thanks in advance.
This may be a forum already started, I apologize if so.

 

Idk what all the plugs are specifically of the top of my head, but here's the speaker wire colors:



You can comb through the full electrical diagram here to try and figure out what plugs are what:
Ultimate TUNDRA Wiring Diagrams Collection | Toyota Tundra Forum (tundras.com)

and the full audio diagram here:
All Years Complete Audio System Wiring Diagrams | Toyota Tundra Forum (tundras.com)