LD4B bypass hose fitting thread size?

[H22A4]

Are the cooling bypass fitting threads on a LD4B intake 3/4" NPT or 3/8" NPT?

 

[lemondana]

Are the cooling bypass fitting threads on a LD4B intake 3/4" NPT or 3/8" NPT?

I have 2 LD4B's. The first one I got years ago has the smaller '69 and earlier size with the cast iron waterpump. The last one I just got at a swapmeet a couple months ago has the larger '70 and up aluminum water pump. The larger one looks like it came that way.