Xenocide

Wave a fag paper around the manifold to find exhaust leaks. So does it do it when the engine's running weather the clutch is up and down or in or out of gear? Sounds like it's changed? If it changes with engine revs then it's not props etc as that'd be road speed. So it's either something on the engine or the input side of the gearbox. Next time it does it, dip the clutch and rev it, see if it changes with revs or stays constant with road speed.

Easiest way would just be to have two fuel tank selector taps and hook one up "backwards" so you have one input and two outputs and pop the return in that. The lightweight ones have switches on them for one position so you could wire it up so you have an idiot light on the dash if they're not both on the same tank which would (might) stop the problem of filling one and using the other.

Yeah i'm sure that'll be fine. The spindle coming out of mine is alot thinner though. Wonder if you have later wiper box thingy?