Hi,
42-4078 and 29-8740 are No 2 & 3 in my parts illustration (see attached) that the petrol tank mounting bolt screws into once the tank is in place.
The rectangular rubber pads 42-8049 (3 off) are fixed (glue or taped) over the top tube of the frame to cushion the tank against vibration. 2 at the front and 1 behind.
42-8012 anti-vibration rubber sleeve fits in the tank mounting bolt hole, the washer sits on top and the bolt goes down through the lot to fix the tank securely in position on the frame top tube by screwing into 42-4078.
40-8039 rubber bung seals the mounting hole at top of tank.
42-8052 are rubber anti-vibration, anti-roll buffers and go one each side on the top of the frame at each end of the crossbar just behind the battery area.
67-8085 is a bridge plate and fits under the frame to clamp the frame top tube between it and the petrol tank. It locates on two studs, one each side, on the bottom of the petrol tank and is secured with the distance pieces, washers and nuts (see photo of one side on my A10).
Once you have everything together to look at how it all fits it'll be obvious.