The importance of measuring bell housing runout.

.004 is the average thickness of a human hair. .080 TIR is alot of miss alignment. It doesn’t surprise me that you have to shim a scatter shield flat to the back of a block. Those shields are stamped and formed in a punch press. Being out of flat will add to the miss alignment so shim it before you indicate it true. To keep it from moving around, shim bolt holes to look like a washer, you know a shim with a hole in it.