My original lightweight starter on the R500 lasted about 3 months before it was replaced with another lightweight one - this lasted another 3 months before aheavier and more robust version was fitted.
This lasted about 6 months but had to be replaced again. The fourth one, has started to perform the 'click' but no start after 2 months - simple enough thing to get right you might have thought...
As for the part, I believe the new one is from the F3000s.
Peter - I might be in the market for another new starter motor !