i kind of do like Zippy, leave the bolts on the cover loose until the damper is installed. however, i open the dowel holes one or two drill sizes on the cover, so the cover seal can float on the damper surface, and be able to exert equal sealing pressure the whole 360 degrees around the damper. i tighten the cover, then the pan.   That's what I do also.
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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