Just a suggestion, why not take the starter off and go to your local dealer with it, let him match it. I once went to Volvo's commercial site near Heathrow, they matched up stuff immediately and at a fraction of the price asked by a marine outlet.
Thanks for the tip, but I do not have a starter at present. so if anyone has a Bosch part no. or any info I would be pleased. One other little problem Heathrow is a long way for me. I live in Norway although I am in the UK 2-3 times a year.
I think it's the same one used by VW, at least for the air cooled engines. Can't quote you a part number, sorry, but I suspect it is different. Many years ago I was told that the Volvo starter has bearings made from a different material from the car version. I cannot imagine that there is a significant difference between them. At the time that I compared them the VW starter was 100 pounds whereas the Volvo was 500.