Flange lightening holes. The drop-the-car-on-the-jack method worked very well, however I found the ribs had a slight cupping in from top to bottom. Putting them back in the dies and finishing them off by placing a block of wood on top and bashing with a hammer trued them up nicely. I will get hold of a mash hammer to make this quicker, as the old Estwing claw hammer needs a lot of swinging to get it right.
1.85 Hours.