My observation over the years is that all body style 76 (conv) had or were meant to have the jute underlayment. Without this the "sloshing" of the fuel while driving is very evident and not in step with the expectations of a mid sixties buyer. The top of the tank was the ONLY place that a sound barrier could be incorporated since the divider between trunk and cabin is pretty well taken up by the well and the folding top and associated parts. The coupe was intended to have the same jute type insulation/sound barrier placed on the vertical section behind the back seat which serves as a divider between the trunk area and the cabin. In addition some type of material was used on the little body panel that seperated the tank (floor) from the vertical section. This silences the gas slosh and I suppose in addition provides a little thermal insulation between the cabin and the trunk. The fastback body style is open for discussion. The 65 interior FAM shows a jute insulator was used, but the 66 for some reason does not show any. I have a 65 fastback with deluxe interior built April 22, 1965 which, as far as I can tell did not have the jute sound insulator. Could it have been there when the car was built? You bet it could but it had the original mat still in place in 1984 when I purchased it from the second owner but no jute mat. Seems odd it would have been removed but there is no way of telling. I have agonized over this question for almost 30 years and have looked at several examples and have come to NO conclusion about the fastback and I hope that someone will provide images or proof that this insulator was or was not incorporated in a Spring of 65 fastback built at Dearborn (or anywhere else, too). Look at the dates in both the 65 and the 66 FAM drawings of the trunk area and post what you think about the change date shown.
