Hey @J.Ukrop Jerry Chins very cool (69) hot rod as seen at the past Estranged Drag's at TMP a few weeks ago. Thanks from Dennis.
Go buy some new ones at Harbor Freight. You don't borrow hole saws cause they're usually about done after you use them. That's like borrowing underwear.
Looks like it was just dipped in a slightly caustic wash like citric acid or something. It really brought out the yellow.