i just put a 95 lightning 351w in a friends mustang,the stock balancer was too short so i ordered the motorsport m-8510-b351 spacer that some people told me to get to align the pulleys,well it doesent fit on the stock balancer,i even tried it on a 87 351 crown vic balancer,doesent fit.is this the right spacer and i need to grind the lip off or something.please help,totally lost here