Hi VW,
Yes 42-4078 is the stub threaded into the frame
Rubber, 42-8012 goes over the tank bolt which is a special shouldered bolt,
it prevents overcompression of the rubber
The square rubber pads 42- 8049/51 in the link are taped to the frame to isolate the tank from vibration
42-8052 rubbers are fitted to the frame to prevent tank roll
HTH
John