Water Outlet Plug

[69 GT350 Vert]

Is this what the plug should look like for a 1969 351W with Automatic Trans and Without A/C? 

Does anyone know the thread size I need to buy? 

Thanks.

[J_Speegle]

Yes for a non-AC car it would have a square top. In your picture the plug below that appears to be domed in my picture. Will have to take a look at my pictures to see if that detail matches

Sorry don't have one to measure the threads at the moment

[J_Speegle]

Follow up. Here is a close up of an original. Appears there as some small differences.

Hope it helps

[69 GT350 Vert]

Thanks. That helps!