Lift the rear of the car in order to get as much clearance as possible.

Not clearly seen but this is the part of the tank where the leak comes off a spot weld.

Remove the two strap bolts which actually hold the tank in place.

The same for the fuel filler neck.

Undo the two clamps on the lower fuel tank hose.

Undo the fuel hose clip that sits just behind the spare wheel well.

Undo the strap bolts completely.

Tank is dropped.

A couple of close ups show the fuel sender unit along with the fuel supply/return lines. Quite impractical is the earth lead that must be removed along with a fuel sender unit bolt.

A better solution of attaching the fuel sender earth lead to the chassis at a later stage.

Here are the two tanks demonstrated.
The upper one is the temporary replacement that my friend Dennis kindly offered in order to keep the 33 running while rebuilding the original one.

You can see the differences between the fuel senders. The original tank has the fuel sender unit tube facing forward (front of car) whereas the replacement tank has the sender unit tube facing backwards.

The same principle is applied to the pipe routing. As you can see the original tank has the fuel return pipe facing forward (front of car)

The replacement tank has the return pipe facing backward (rear of car).
This is of no major concern as the return pipe will be routed using a flexible 8mm fuel line.
The replacement tank comes off a Marelli - IAW fuel injection Alfa 33 whereas mine is a L-Jetronic one. I don't think that this has to do strictly with the engine management system but it all depends what parts were available during assembly or the enhancements during production.

Bosch L-Jetronic fuel tank

Marelli IAW fuel tank.