Holy ultimate confusion...
Well, my 'box is an FM so I suppose that's a sign of bad things. My question is what the fundamentals are of the change? I had this issue when changing clutches as well as now with the sump. With the clutch, I believe it was the number of splines on the shaft of the box that changed.
I also notice oil capacity increased from the MY91-93 to MY94-98 cars. However, there appears (that I can find) no physical difference between the sumps that would account for this. Of course, 300ML is a fairly small amount but it has to be there somewhere.
The seller has offered me a refund of the money for the sump. It was a small cost anyway, if I'm honest. But I'll be out the cost of postage to send it back. If it will work and I just need to modify something about it, that's fine. I need to strip it down for cleaning anyway. Based on the bits of ferrous metal beneath the baffle, I'm going to say the donor car suffered a rather traumatic end.
As for welding the existing pan, I can do that myself. Brazing ally isn't technically difficult if you watch your temperatures. The issue is that my 9K is my only car and I can't really afford the time of having it down. I'm not sure how bad the total of the damage to the lug is. It may well snap clean when I remove the sump. In which case, I would need to braze it inside and out and will need to thoroughly clean it before doing so (as well as remove the epoxy I tried using to see if it would slow the leak until I could acquire a new sump). For reference, don't try any epoxy. Nothing can stand up to oil as much as they may claim otherwise. The part would have to be removed, cleaned, completely dried and allowed to cure some 48 hours before refitting. If you're going to do all of that, you may just as well braze it proper and be done with it for a lifetime.
So yes. This whole thing is turning into a massive brain-ache.