Starter Motor Issue

[Dave Mann]

    Here's a photo of the two ring gears next to each other. The correct ring gear fitted perfectly heated to 250 degrees C it dropped on and locked on. After giving it some thought I think the wrong one was made for a Seven and incorrectly machined. As Lucas were the main supplier of starters I can't see them making starters with different pinions for similar sized engines. Would this be the cause of some rear mounted starter mountings failing? If I've found one there are bound to be others around.