Yes, the Judge uses D8 to hit and D6 for damage.
D6 is the default for everything. If you're told to roll a die, roll a D6 unless it explicitly tells you to roll something else (D3, D8, Peril die, etc).
Got it, thanks for your insight. It can be difficult to remember everything the more you acquire. Especially when you have several weapons that all use different dice for each action. The Judge, The Punisher, Thump Gun, and my rancher's default upgraded Hunting Rifle...I'll need to pay closer attention! Thanks.