I just rub it on a flat table with some emery paper on it. I have also filed a bit off of it. U can see where the file is removing aluminum. Just make it flat/level. Kim
A few years ago I built a 440 with a Indy rear main seal housing. Couldn't get the side seals to go in correctly with it. Dan Dvorak told me to get rid of the after market housing and use a stock housing.
