I was crawling under my ‘63 today, looking and learning. Found the “25” on my front dif, yep, a Dana 25. Then scooted back to the driver’s side of the rear dif and saw this... looks like maybe heat or something? No sign of any lube leaking, maybe from the casting? Botched repair? Maybe not holed all the way through, hopefully? Ever seen anything like this? A concern? Thanks for looking! Ray in central Texas.