I made my car level by putting a level on the rockers, then jacked the trans so it was pointed on the rear. I then just used a harbor freight $4.95 angle finder and placed it on the end of the trans. It was 4 degrees down, I adjusted it to five degrees down figuring it was easier to add a spacer to lift up that to re-cut to move down.
This may not be the ideal way, or correct way, but it worked.
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