Opposite voltage regulator. One end is a spade plug and the other is attached to the body of the alternator with a short screw.

Reason I'm asking is that the pick and pull alternator that I installed on my 85 300td is only giving 11.8 volts. I think the issue may be a bad ground, and maybe I can use this spade connection to ground the alt directly with a new wire and connector.

Attached Thumbnails

 

__________________
2009 E320 Bluetec 117,000
1995 E300D 306,000 Sold
1996 Ford Taurus LX 130,000 Sold
1985 300TD Still 225,000 Sold
2016 Ford Fusion 24,900

I think it's a radio interference suppressor.

__________________
2009 E320 Bluetec 117,000
1995 E300D 306,000 Sold
1996 Ford Taurus LX 130,000 Sold
1985 300TD Still 225,000 Sold
2016 Ford Fusion 24,900

Yup.

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.