Yo may want to also take apart the mounting adapter plate screws.Mine worked loose after about 18k miles,allowing the starter to hang down and not engage.
One of the long screws bent,
When I called they said just put it back and recommended some loctite .I thought why didnt they loctite it when assembled.
Anyway besides that I think its a nice upgrade.
I didnt use a shim because I wasnt aware one was used.
Tom