130 rear light wiring issue

Hi all, my 130 tipper is losing its rear lights. Drivers rear indicator shows I'm getting 8v maximum, offside brake light is now the tail lights, near side tail lights don't work.
I've checked the bulb holders etc but I think the issue is the loom. Does it have a junction box on the bulkhead? I priced up a new rear chassis loom but £454 plus vat is a little over the top.

Any suggestions great fully recieved.

Earth.

ok, ill be more helpful.

when you checked for voltage, did you use the lamp earth, or a known good earth, if the former, sounds like the earth has gone bad, where this would be on a 130 I do not know

what year/engine is it, looms have changed slightly over the years, and earth in different places.

Now you say it I used a new earth and lights earth. I did however have a starter issue and had to run a new earth straight to starter to get it to spin. I also have a battery drain over a couple days. I checked each fuse on the board and found a 5 amp drawing current so pulled it and problem is less.
Poor old truck, just needs done tlc!