my 1975 car seems to have a 2 prong plastic type socket, which appears to have an internal connection to the speedo can for ground.

my question is why does this socket have 2 spades?

in my 1972 car, the white/green wire was cut and this light was spliced into the regular dash lights but this car seems to use a metal socket that grounds directly to speedo can.

I want to revise my wires once again to allow for a high beam indicator light in my speedo. thoughts? should I use a metal or plastic type socket?

I know - or think - that some of my lights are in plastic dual spade sockets because they are feed ground thru the ecu - like oil pressure dummy light?

thus wondering if there are 2 kinds of plastic sockets?

thanks

metal socket grounds to instruments common ground. .
plastic socket = no electrical conductivity therefor it has to have a ground wire connection

The plastic holders have a metal tab on the side that grounds the holder.

i'm assuming there are at least 2 kinds of plastic sockets, one with ground to can and one that needs ground from ecu.

here also is a pic of a plastic socket without a grounding tab, and this one seems to take a different bulb than other sockets.

thanks guys!

jim