looking to add one to my upper hose. what size adapter do i need. i see them all over ebay and I'm not sure what size i will need. reason i say I'm looking on ebay is because i see u can ground the housing so the auto meter can read properly. any help on this from people who have done it would be great.

U'll get a better reading if u mount the sending unit/adapter in the heater hose (not the rad hose), close to the t-stat cover. That heater hose is 3/4" I.D.

Ok I'd still like to know if other people have done it and know what size it is

Not sure what u r wanting????? As stated in post #2, the heater hose is 3/4" I.D. An adapter (the piece that the sending unit screws into) that fits inside the heater hose would need to be 3/4" O.D. Something like these homemade sending unit adapters.......

The sender body is easy to ground, rather than it's housing.
I have one in the heater hose that attaches to the 'water pump inlet tube'. It is always flowing coolant.
An infra-red temp gun is good to poke around with.

Which "inlet" tube?.....heater core or water pump. The sending unit needs to b mounted as close as possible to the t-stat cover, in the 3/4" heater hose.

Hose between water pump inlet tube, and heater core.

That's the cool/cold line and will yield inaccurate readings.

The sending unit needs to be located where hot coolant exits the motor, not where cool coolant enters the motor.

I see. I should have realized that since it's called an 'inlet' tube.
So can I just install it on the other heater hose? Would that be correct? It's a 1996 and still has the Heater Control Valve.

Mount the sending unit in the 3/4" heater hose as close as possible the t-stat cover. The heater control valve should be a non-issue as the coolant bypass "loop" is ahead of the heater control valve......and presuming u mount it as close as possible to the t-stat cover.

^ Thank You!

Have u considered eliminating the HCV?.......the Factory did '97 up.