Thanks everyone for all of the information. I'm sure I will have a lot more questions.  I really do appreciate all of you taking time to help me out.  This is my first mini and I bought it totally disassembled so it's like one of those 1000 piece puzzles.  All of my experience has been with American cars and this has been a challenge.  SO many unusual things on this car.  Thanks again, David

The little plastic fitting under the seat is worth more than the fuel pump!

As those guys stated, they are vent holes for the electric motor in the pump (modern pumps also have vents but they use a kevlar membrane to protect the vent from accidentally ingesting any water or dust). Since nothing like kevlar existed in the '60s, SU used simple rubber hose to route them to a clean area of the car (like, inside the boot, or under the rear seat) to breathe clean air from.

This vented area of the pump is completely separated from the fuel side, so they are perfectly safe to direct into the passenger compartment.

Norm

Originally the vent(s) connnected via a plastic tube to a plastic fitting under the rear seat.

that is correct.  there are two barbed outlets.  are these left open or do they connect to the vent tubes on the tanks?  thanks, DavidDavid

Pictures would help.  erhaps you are talking about the small holes sometimes outfitted with barbed fittings.  Those are vent holes.

Finally finished all my plumbing: maybe??  what are the 2 small outlets on this pump for?