I do have a few 69772 on hand, I'll try to remember to look on Wednesday when I am back in the shop to confirm the thickness. In taking saws apart I have found no washers, fiber washers, steel washers, and fiberglass reinforced polyester washers used between the oil tank and the fuel tank.
The insulator between the fuel tank/airbox and the cylinder is thinner on the 70 cc saws and thicker on the 54/57/60 cc models and pretty well accounts for the spacing between the fuel tank and oil tank so that spacer up front doesn't seem to be a big factor in the way the saws go together or perform in the long run.
Many saws also have/had a fiber insulating washer between the shroud and the airbox (68581), many saws are missing this one as well. I have a few of these also, again I will try to remember and measure the thickness of those too.
Mark