TH400 cooling line inlet thread pitch?

[first64riv]

In my ongoing TH400 leak saga, I am at the home stretch.  I find a leak at the fitting so now I need to replace it.  I've had it off once but never bothered to measure it.  I need to know what the 1964 TH400 casing was tapped with for the cooling lines.  I think it's 1/4 NPT into the case and i know it' a 5/8 flare fitting on the line side.  Is my 1/4" assumption correct?

 

Chris