Mark III roadster tank uniformity?

I have two Mark III roadster tanks which I believe to both be OEM. The distance between the front mount studs is 6 inches O.C on one tank and 5 inches O.C. on the other. The rear mounts are both 6 inches O.C. on both. The front frame mounts have 7/8 inch holes which are about 5 1/2 inches O.C. so I thought maybe the large mount holes were to accommodate a large tolerance in front stud distances. Does anyone know the proper distance of the front tanks stud?

2 metal Roadster tanks, one fiberglass Roadster tank and one metal Hi-Rider tank and all are 5 1/2" center-to-center on the front mounting studs. Rear studs on the Hi-Rider are 5 1/2", metal Roadsters are 6". Fiberglass tank has no rear studs.

Like frames, gauges and some other components, not all were sourced from the same suppliers.

Danno said:

2 metal Roadster tanks, one fiberglass Roadster tank and one metal Hi-Rider tank and all are 5 1/2" center-to-center on the front mounting studs. Rear studs on the Hi-Rider are 5 1/2", metal Roadsters are 6". Fiberglass tank has no rear studs.

Like frames, gauges and some other components, not all were sourced from the same suppliers.

Click to expand...

So I'm guessing the studs should be 5 1/2 inches apart from you having two exactly the same. But I see no way to expand the short one or shorten the long one without damage to the tank itself. I now know why I could never get the short one to center on the neck as both studs are right against the frame holes and there is no wiggle room.

Fibreglass roadster tank has 6" studs and metal Hi-rider tank has 5 1/2". Both fit on bike as holes in frame are large enough. Rather than rubber spacers you can use head steady/ exhaust pipe rubber bushes with penny washers.