Oil Leak

I have had an oil leak for a long time and thought it was the Oil cooler O rings as there was oil all over the front diff and also dripping from the sump plug also the side of the filter housing was covered in oil. Fitted a new filter top as the nut was sheared off and that cured the wet filter housing new O rings in the oil cooler pipes but still leaking from somewhere. Next thought was diff leaking and found diff bolts loose and fitted new pinion seal and tightened the bolts cleaned off everything and still a leak. so got under the car and cleansd everyting off and found a hairline crack in the sump which must have been got over the rough roads in Mogolia or a rock hit it but it was right above the diff and herd to see.
Has anyone else had a cracked sump?

No. But I have a leak I can not find. Perhaps mine is cracked too! I'll have a close look next time I'm under it. How hard was it to spot?

Clean it all up and then check after each drive with an inspection lamp. The good thing about oil is that it is easy to spot!

Mine is a diesel so dont know if it will be relevant for a 4.6
First i thought it was oil cooler O ring as there was oil all down the side of the sump and all over the front diff.
Then I found the Oil filter O ring was leaking and as I was due for an oil change and renewed my timing chains let it go.
After I had done T/Cs it was still wet on the diff and found the diff banjo bolts loose and while at it renewed the front flange oil seal.
There still oil around the sump plug so cleaned it off checked sump plug tightness and cleaned oil off again.
went for a run still leaking but this time when i went under the car was at full height and I could see above the diff and when I cleaned the oil off I noticed a thin black line of oil seeping out .
Have made up some epoxie resin and put on and seems to have cured it for the time being.

I just changed my oil cooler hoses. They were certainly weeping, the leak is less now but it's still there!

I've got oil in all the same places, oil filter, sump plug, diff housing and even the bell housing!

I think it's the front (and rear) crankshaft oilseal. The front one is easy to do I'm told, but the back one needs the gearbox out so I might just leave it and keep topping up!