water sending unit

Road/Rage said
I've got the 225 3.7 liter engine. Anyone know the size of the sending unit threads? When I eye ball it it looks like a 1/8th. Everyone I ask around here says it 1/4 NPT. It looks like fine thread. Anyone know for sure. I was told to switch it to mechanical gauge. In the gauge kit it only goes down to 1/4 NPT.

Here is what Vixen has. It is a 1/8" port.
VIXEN TEMP SENDER.jpg

Next is the original 170 I pulled out of Vixen. It is also 1/8" NPT.
170 TEMP SENDER PORT.jpg

Finally is my 1977 model closed chamber prototype head. It has two 3/8 NPT ports. So you could say the people you talked to were WRONG.
1977 HEAD TEMP SENDER PORT.jpg