12Si Alternator Install Diode with Battery Gauge

[andrewpclayton]

Working on a 69 GMC 1500 and I have been following VetteVet's posts as best I can, but this is absolutely not my strongest area. Hopefully he can chime in

I am swapping in a 350 engine from a 77 4wd (I think) that has the alternator on the passenger side. As of now the engine is out, and nothing is plugged in but I want to have everything ready to plug and go. Will be installing an alternator from a 85ish C10.


I have taken the wiring tape apart and removed the plug for the external harness, so its set for the brown wire to go from firewall to #1 on the alternator

I have a battery gauge, I assume this means there isnt also a light, thus I need the diode?

If that is the case, I cannot figure out what a diode even looks like, nor which to get.


Can one of you, any of you, all of you tell me

A) am I on the right track in terms of from the harness, the brown wire going to #1, the red going to #2 and the junction box, and power from battery via starter

and
B) if the diode is necessary, can someone link me to the correct unit to buy?

thanks!