Aluminium sump drain plug?

[smiffy1071]

Hi boys, is anyone aware of any differences on cast Aluminium engine sump for Aircon cars?

The car I'm working on BX 17TD has an ally sump ready for aircon, but none of that is fitted.

It has two holes at the back, one for the drain plug, and one for an engine oil temperature sender which I want to fit.
My Current car also a BX 17TD also has this and full aircon fitted but the difference is, these holes are a different size.

I've bought a temperature sender to suit a BX GTi/ 205GTi which is I think M16/1.5 and of course it won't fit, as the holes on this sump are the same size as the coolant senders in the thermostat housing which is I think M14/1.25.

Anyone come across this before? As it is, it looks like I'll have to wait till my current car runs out of MOT, then swap the sump over.