jOHN,
Not debating you here, but when I look at this: http://www.ebay.com/itm/OIL-TANK-OLD-BSA-B31-32-33-34-A7-10-FLAT-SIDED-GOLD-STAR-has-a-dent-repair-/201366806198?hash=item2ee2659eb6&vxp=mtr
I still see a bulging outer face, not flat like the flat tool box. It seems that the difference may be in the radii where they turn back toward the seam. I'm just not sure. Care to clarify this for me?
Editing: The more I look at this the more I am seeing it as flatter with smaller radius corners but still not seeing it as "flat".
Richard L.
Sorry for the (slight) ! delay posting this but only just read the query ...I can confirm absolutely that the flatter sided oil tank and tool box on the swinging arm A range changed after 1956 ..I am certain of this as My Own 1955 December 12th 1955 "Golden Flash" (in other words a 1956 season with Ariel hubs) had the flatter ones from new as I am the 2nd owner from new and can say with certainity ...Im almost sure the more rounded versions came out in 1958 ?