RUBBER VIBRATION MOUNTING STUDS REPLACEMENT FOR OEM #50235-63. FEATURES 1/16 X18 THREADED STUD ON ONE END AND 5/16 X18 THREADED HOLE ON OPPOSITE END.
Source: Custom Chrome
This is just the answer for custom builders. These studs are perfect for mounting gas and oil tanks. Sold in packs of 5 (unless otherwise noted).