second set of head lights and trailer plug earthing something chronic

[btd19m]

so as near as i can tell the trailer plug (5 pin) and the second set of head lights (high beam lights maybe?) are earthing enough right now that when you turn on high beam the lights light up for under 5 seconds and then the battery is dead flat. i am planing to just use led light bars/light force 240's on the car and its all wired up for it. (*old owner had 35 watt spot lights)  just need to figure out where the problems with the battery is. i have a battery in the tray at the moment (12v truck battery) and i have had to jump start it a few times off that. at the moment the lights are disconnected (removed the bulbs and put a peace of tin jamming the high beam switch) and ive disconnected the trailer plug by pulling the fuses. im assuming the trailer plug was a factory fit. the fuse box is 100% unmodded and theres a trailer plug fuse. also the trailer plug is smooth and theres not a single after market cut or mark apart from 3 drill holes made by the old owner. the issues seams to be the trailer plug earth i think. all the other wires have a sort of boot over them and its intact but the trailer plug earth is just hanging down. now there is 20cm+ of lose wire stuffed up in the tray and its all held together with 100m\h tape (old australian tape made from fiber instead of plastic. it does look a lot like the trailer plug wires were broken at some point as the "newer" wires run from the head lights the dash cluster the dash itself and theres wires from the turning lights and the break lights too. i have shattered my rear lights but lucky for me the old owner had done so before and a aftermarket dealer near me makes brand new datsun 720 tail lights for the stainless bar on the back of the dual cab. 

 

also replaced the starter motor yesterday. its was jammed on and rusted suck. rust was bad enough that the wires were touching and the sound under the hood was in the end the fact that even though the key was back to acc the starter was still endlessly turning. im getting new spark plugs and a new distributor cap soon as the current one has a 20-30mm hole in the middle as a breather hole. it lets water in and its making the car extremely hard to drive on the highway or in the wet or until after midday and before 600PM 

 

other then that its smooth electronically as far as i can see 

 

 

heres the short list of parts i need. 

 

distributor cap

battery (current one is from 2002)

trailer plug (have a factory one for a d22 unsure if its going to work at all)

rear lights (have both sides. both brand spanking new lights. with looms and super bright bulbs) 

may need a bigger alt

may need to replace the inner set of head lights and the outer set seem very dim

need to find out what bulbs to get for the lower set of lights as 1 of the park lights and 1 of the indicators are blown

need a bulb for the inside light as its been missing one for over 10 years (tested and working and getting 12.1v)