They were supplied by Marine Projects in Plymouth. When I need a new one for my old Sigma 362 they supplied it. Try lookin gup their number and giving them a call......
My friends 362 was replaced last year.
when it was cut out from above we found the p bracket had a bronze rod passed (about12mm through theside of the bracket. this was sandwiched between two pieces of hardwood and screwed dowm into the grp and then a small mountain of glass and resin piled on top.
The wood had worried and created some slack with bracket moving about 1-2mm.
It was put back in the same manner but the hardwood was swapped for s/s or bronze i cant remember which and professional brought in to glass the bracket in place.
Not had any problems since. He bought the p bracket from a firm in plymouth, not of their name. i will try and find out if you would like to know.