I took a piece of 1/8" thick self adhesive foam rubber strip and placed it on the tank and trimmed it to the speedo plastic bezel w/ an x-acto, OHH so very carefully,, helped w/ the noise a lot. Been years ago, so, I dont remember what is there that could possibly fail to stay in place.

When ya pull the tank, before ya do that, pull the hose from the carb, put it on prime and drain it into a gas can,, AND, prepare a place to set the tank down so the speedo cable isnt in a bind. Once its in your hands, its hard to locate a Safe place,,
Shouls all else fail, super glue just mite be your friend.