If the oil is leaking from the area inside the UJ as indicated then the oil is travelling along the splines of propshaft and weeping through the welch plug that blocks the end of the front yolk. If you jack the rear up really high you can withdraw the shaft with little or no oil loss to enable a closer inspection. See link attatched for picture to clarify. Hope this helps.
http://www.rimmerbros.co.uk/Item--i-...FeXMtAodBTQAbQ