Slick 60's

As I'm going thought my 66 F-100 wiring system, checking all of my grounds, I came back across a mystery capacitor connected to the Voltage regulator 4 prong connector. It has an in-line male/female (factory) connector located beteen 4 prong regulator connector and the condenser. The condenser is mounted by same screw that mounts the horn relay to the body, but no ther is no other connection to the relay.
I have two wiring diagrams and this condensor is not shown in either of them. The closest clue is wire 152 (1966 wiring diagram )that is shown coming out of the 4 prong plug and terminating in the middle of nowhere on the diagram.
I looks old, and I'd like to replace if its the culprit behind my elecrtical problems.
Does anyone know what this is for, and where I can get another one?
Thanks,
Vic

My guess is that it is the filter capacitor installed for the radio. To cut out some of the hum in the radio from the alternator. To test the cap short the hot wire of the cap to the ground of the cap, but make sure there is no voltage connected to the cap. Then check it with the ohm meter. If it has resistance its probably bad. Or just unplug the hot side of the cap to take it out of the trucks circuits. What kind of electrical problems are you having.

Fist of all its my dad's old truck so I get to blame him for screwing things up (for once)
Its a 1966 custom cab (full gauges) ithe an I-6
It started with the gages not working.
I tested them an they all work with about 3 volts dc.
I bought a new instrument votlage regulator (IVR) from ford and it worked for about 2 weeks (that is my gages worked). They alway go badd the same....the fuel gage gets to 1/4 and the it getts hot and turns off (grounds out)
I took it apart and it looked fine bought I bought another and it never worked right.
2 years later (last month)
The truck died, battery would not charge.
Replaced battery, ad it died in a week.
Replaced alternator and its OK but it kept over-charging the battery (poping hissing and visible moisture)
replaced the Voltage /current regulator (main one under the hood)
Still the battery was geting over charged...
I think I solved that because the engine to froame ground was broken at the connector. (it was too short I think it broke when the engine moved)
But the gauges still drove me nuts so I bought ab "elecronic" IVR that is smoother than the old elecromechanical ones but it still wont read over 1/4 on the fuel gauge.
Vic