Hot Rods 50 Flathead temp gauge in block

Does anyone know the thread size (coarse) for a temperature gauge that fits in an offy head for flatty. And where can I buy the gauge that sits right on top so i can read it on the head. Helping Pop with his old car.

 

Moon makes the gauge. Try any of the Alliance members here on the HAMB that sells parts.

 

Best get one for each side.

 

The hole in the head is tapped 3/8" tapered pipe thread. You can use reducing bushings to match the guage if it is smaller.