Installing sensors on new motor, do i need to use thread sealant on everything?

[UATahoe]

Okay, i am installing a new motor into my 87. I have 3 temp sending units (2 were stock and 1 is an add on for my electric fans), the knock sensor, and 2 fittings for 2 oil sending units (one installing on top by the distributor and one by the oil filter). Just curious if i need to use thread sealant on all of these when i install them? 2 of the temp sending units mount into the heads and the other mounts on the intake manifold. Knock sensor obviously in the block. Was just curious what everybody used to make sure you got a good seal and avoided leaks.