9.5" Ring Gear Differential Fill Plug

[Kubs]

Anyone know the thread size for the fill plug on my 3/4 ton Yukon rear differential? Its a 2000 with the 9.5" ring gear. The square drive rounded out and I need to replace it.

It looks to be around 1/2 NPT but not 100% sure.

Thanks

Edit: A 1/2" NPT plug fits in the hole.