well are you sure that block did not need the plastic cover? older tin cover needs dowel pins to line up the seal up to hub. the front of new block. has no pins to help center it up. it has shoulder bolts to help center the plastic cover so at this point with the tin front cover if you block as no pins. the hub centers it up on seal you need to keep cover bolts loose till damper is on this helps center it up then draw all cover bolts down