From what I have hear - the G/S, (and hopefully the GS), used the same "bail with a rubber" that wrapped around the backbone tube, as opposed to the metal strap with two holes, to accept rubber cushioned screws with big plastic nuts to hold the rear in place.
The front is the same on all the post '70, I believe.
Length might throw you a curve-ball. The R65 tank is longer, I believe.