How do you remove the fill plug on the differential on a 1983 C10 (2WD). This is the 10-bolt rear end. As far as I can tell, the fill plug is on the passenger side of the diff and requires some sort of special tool. Either that or the previous owner stripped it out. At first I thought it was an Allen or Torx type nut. But it's mostly squared off - it seems like something between a 3/8 and a 1/2 ratchet would fit. Any ideas ? Do I need to buy a 'Pipe Plug Socket' ? Those aren't too easy to find from what I've seen. Only online so far through www.etoolcart.com