200tdi alternator bolts size.....

I have a defender 200tdi engine. After getting chassis galvanised and engine reconditioned, found out the chassis guy did a half job putting things back together. He is just one issue away from a solicitors letter. Latest issue is battery running low on a short run. Had a look underneath bonnet to find belt had come off the alternator. The reason- the alternator had come loose as it was 'fixed' with just one of the three bolts, and no washers!

So, anyone know what size the bolts are as I have nothing to compare them to nor anything to try?

Thanks

there all m8 but you need to measure lenght

What length m8 is this?