Are the square holes above the power brake booster on a MK II S meant to have those white plastic inserts so the 8TR (and 4TR?) controller can be screwed in with self-tappers? If so, where can I buy some, and is there a particular screw that should be used for originality?

See photo below (not my car - thanks to whoever's it is).

There will be two holes near there to suit the white inserts, but the 4TR does not screw into them, it simply screws into two small holes in the inner guard. The plug beneath the regualtor obscures one of the plastic plugs.

The screws are a little hard to describe as I don't know the gauge that is used, but the heads are about 8mm across and are the usual BMC self tapper used in other parts of the car.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Thanks Mick. After your response I had a closer look and noticed the two square holes are at the same level but the 8TR holes are offset (high and low). I now remember that the square holes (with plastic plugs) are for the old control box that is for a generator charged car.
Are the square holes left empty when the 8TR is fitted or were they plugged with something?

Mine were actually plugged when I got it, so I put the plugs back in....They'd lasted that long, who was I to toss them out

_________________
SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.