I still have nightmares about changing the fuel tank on that vehicle! Laying on a pallet to keep me above the water line of the muddy puddle that had formed under it, subsequent to removing the old one...
Interestingly the fault with the old one was it would run out of fuel going up hills, with 1/2 a tank of petrol. We found the issue to be a hole in the tank pick up pipe, which we only uncovered after cutting open the old tank. Some prior, poorly implemented repair would seem to be the cause of the hole. We ran it off a jerry can for a while, and it got me all the way from Mikes to the middle of a large, muddy puddle at Beltring before running out...showed my MPG calculation for that trip was spot on!