Does anybody know how the Jump start terminal black plastic box DBC10501 is attached to the bulkhead ? The brass threaded post on mine sheared off when I was re-attaching the lead to it and I need to get it off the car to fix it properly. I managed to get the broken piece out of the large brass long nut that’s used for attaching the POSITIVE jump lead to, it looks like it’s been fractured for a long time which explains why it broke when I tried to nip it back up but I need to remove the box to fit a new threaded piece.
IIRC, the other “end” of the post comes through the firewall and it’s secured with a large nut. That connects to the main harness of the car. In the case of mine (94, battery in the trunk) there’s also a heavy cable that runs back to the battery.
I think you might have to pull the dash to get at it, but not sure about that.
Mine must be different Larry. The ‘other end’ of the post that’s broken does not pass through the firewall, at first I thought it must do but it definitely doesn’t, I can slide a credit card between the plastic box and the firewall. The terminal doesn’t connect anywhere to any other wiring or electrics, it’s sole purpose is to provide a place to clip a jump lead to. Like your car my battery is in the boot, I’ve just been out and traced the other end of the lead and it’s actually for a POSITIVE connection from a jump lead and NOT a negative like I first thought. I think you are right regarding access to whatever actually holds the box to the firewall in that the bloody dash would have to come out to remove it.
Been a while since I stripped the parts car Casso, apologies for the “misinformation” lol
No need for apologies Larry 
I appreciate you taking the time to reply, I too made the assumption it must pass through the firewall, that was until I realised it was NOT an earthing point but actually for the POS connection of a jump lead. I found some pics trawling the net and originally they had a large red + sticker on the flip up lid, long gone on my car.
Cheers 