VX275,
Ah, yes , many thanks, I do remember the early Shacks' bag tanks.
My question came from a remark I heard at Cottesmore in the early 70's when an Argosy man stated that he would rather not be in a Herc. in a combat zone as it did not have self-sealing tanks, unlike his steed.
Unfortunately it seems to have been a prescient remark.