6.4L Temp Sensors

Recently ran into a little issue with tightening down my temperature sensors. The ECT, EOT and FTS are all the same exact sensor. The problem being that I keep snapping the new ones when installing them. My Ford service manual calls for 18Nm or 159 lb-in. Ive checked multiple torque wrenches for their consistency before starting this engine build. Re-checked after this issue and we can rule that out as they still are within spec. To add further I can put in my three old sensors and torque them down to book value no problem. But these damn new ones snap every time. What am I doing wrong? Was there a TSB for a new torque? Or is true they just dont make them like they used to? Im reluctant to just go hand tight in fear of a leak, it backing out or substitute loctite because if I had to remove them later they may snap as well.

LOL WTF!

I've never ever torqued one of these.....

Some dielectric grease on the o ring and then hand snug.

Weird right??? I kinda figured since I had the books Id do everything to spec. Lol never thought it would come back to bite me. Thanks for the advice though!