Differential filler plug size


gallo vicioso
What size tool do I need for the filler plug in the diff?
I'm going to change the rear gear lube and want to be sure I have the right tool before I start.
3/8" square socket. I just use my 3/8" drive ratchet with no socket attached. Spray some P-B Blaster or Liquid Wrench on it before breaking it loose as it can be tough to remove if it hasn't been broke free in a while.