Threaded port in exh. manifold for EGR tube, size?

[jmgtp]

I'm using a 1996 3100 rear manifold from a W car on my LX9 swap in my Grand Prix.
I will not be running an egr. There is a threaded port in the exhaust manifold for the egr tube (which I don't even have). Does anyone know the bolt size that would fit so I can plug it?

I thought about welding it closed but the two issues with that are 1) I may want to add an EGR later, and 2) the manifold is already bolted up the head and I don't feel like removing it.

[bszopi]

I know I used a brass plug from Home Depot in mine, but that has long since burned up, so I can't even measure it for you, and sure don't remember the size. I want to say it was 3/4" NPT...

[Azrael]

You can get just the exhaust manifold plug from the egr delete kit at the wot-tech store.

Just noticed they're out of stock at the moment.