I had this problem aswell, what a pain the arse it is, its a direct replacement SMIC but for some stupid reason who ever made it didnt think about just tapping an M6 thread in there to make it a replacement they used some stoneage thread no one knows exixts anymore. I stripped everything to bits went to fit it in and oh the bolts dont fit. I took mine to B&Q, Motorfactor places and a bolt specialist and couldnt get anything to fit what so ever, so out came the Araldite and I glued little lengths of M6 thread rod in the holes and used bolts to hold it onto the mounting points and thats the only way I could get around the problem.
Its stupid really because for the price they seem a well built replacement SMIC and they probably work very well but what a shame they are sush a pain the arse to fit properly when all they needed to do was to tap the right thread in there in the first place, it wouldnt have taken anylonger or cost anymore but probably couldnt be arsed to find out what thread it actually needed to be.
Anyway, Il shut up now and just say Araldite is the way forward