If you heat the flange up enough the bolts will come right out like a hot knife through butter
Be careful not to strip the bolts with the impact gun, it is hard to get in there enough to fully engage them.
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-1993 Mustang, 900rwhp 03-04 cobra based 4v swap, full Griggs setup, project underway
-1994 Ranger w/ 427cid windsor (daily beater)
check it out!