On the 5.0 SC the main bearing cap bolts are a Ribe profile, like Torx but square ended spokes. A Ribe M9 is too slack, M10 too big. Torx equivalents are either too sloppy or too large.

So, like the head bolts, there must be a special JLR tool, like a Ribe M9.5.

Does anyone know the tool part number so I can order it? 2010 5.0 SC Autobiography Overfinch in Bentley Silk White pearlescent, 22" Overfinch wheels with 285/35x22 tyres

I am currently half way through a full engine rebuild on a 5.0 Supercharged engine and can confirm that the correct tool is a Ribe M10.

I took a sample bolt to a specialty tools shop and bought the M10 which I can confirm fits perfectly - I used it 2 days ago to torque my main bearing caps. One may find some varnish build up on the bolt head which makes it appear that the M10 is too big but it is definitely correct and a small amount of persuasion will make it fit.

Either my bolts are different or my Ribe M10 is different. The spokes on my Ribe M10 are 2mm wide. The corresponding spokes in the bolt head are only 1.8mm wide, so the M10 won't fit.

On another forum it was claimed a reduced diameter T55 worked. So I spun up a T55 in my drill and applied a metal file. It didn't take much metal removal for it to fit nice and snug. 2010 5.0 SC Autobiography Overfinch in Bentley Silk White pearlescent, 22" Overfinch wheels with 285/35x22 tyres

Is it possible that your Ribe M10 is actually a Torx Plus? They look the same but the spokes/teeth are wider on the Torx Plus.

But anyway, its useful to know that one can easily modify a Torx to fit the Ribe head.