I have a 1996 extended cab 2wd Tacoma. It needs a new Engine coolant temperature sensor but the book I have doesn't show where it is on the motor. (2.4)

I'm not sure but this may help. I haven't needed to find the ECT on my truck. The link is to a 2003 Tacoma shop manual. I would think your ECT is in the same location.
http://misc.mmdsi.net/tacoma/tacoma-manual/
In volume II find the Fuel section. Go to this section for instructions on removal of the ECT.
Repair Manual##SFI (2RZ-FE, 3RZ-FE)##Engine Coolant
Temperature Sensor##Inspection

Hope this helps.
Clifton