No new fitting was able to be found. The existing fitting did have some threads which were slightly squashed due to incorrect thread compatibility but as the lead-in threads were undamaged, it was possible to get a good straight start on screwing it into the turbo, and so I was confident I could do this without causing any damage. Basically I greased the fitting liberally (to avoid galling the thread) and then carefully screwed it into the turbo housing, where there was a little resistance about 1/2 way in, but nothing too concerning, so I proceeded to tighten until I could feel the fitting bottoming out on the taper seal at the bottom, and it was all nice and tight. No major problem, and it got the car back on the road again. Word of warning to anyone else fitting an Earls inline filter with flexible oil lines on an FG model car; The hex extension fitting on the turbo must be removed, so that the flexible oil line fitting is screwed directly into the turbo housing, as the thread in the extension fitting is INCOMPATIBLE the oil line fitting. Unfortunately it is so close, that this may not be obvious to the untrained eye, and worst case if fitted incorrectly, the fitting could separate while driving, making one hell of a mess, and as it is near the exhaust, potentially cause a fire.