Is this an auxillary tank?

[Lucy and daisy]

Hi everyone....

I just brought a sweet Patrol 1987 160VRG in beautiful condition... my only issue so far is that when filling her up diesel spewed onto the road, I tightened the rings around the hose which connects to the tank (which were loose) but in doing so I noticed 2 things.

1. that there is another large hose (which comes from a T junction from the main hose which goes to the fuel tank) this goes to a large black tank (or casing) directly above the spare tyre mount. I was wondering whether this is an auxillary fuel tank or a casing for something else?

2. the rubber seal just behind the fuel door appears to by shot. Are these easy to come by and easy to replace?

I would love some advice on these matters. I have only started to learn about diesel mechanics and this car will no doubt teach me plenty.

Thanks

[Airstrike]

Hi mate and Welcome. I dont mind much about the diesels but I have been taught plenty on the petrols whilst i have been a member.

Pop up an introduction about yourself and the car with pics if possible and I am sure someone here will be eager to reply with a possible solution.

Cheers

[Lucy and daisy]

Just looked up the manual online and realised this must be the main fuel tank and the other one I have got is the auxiliary... hooray for long range fuel tanks!