Pretty much all american V8 engines have a spot that the temp sender installs into the intake manifold. It should be towards the front and off to the drivers side.
Not sure if you have a mech. sender or electric.
If its mechanical you'll either have a coil of line with what looks like a spring/metal wrapped around it or sometimes is just a black line/hose and then at the end it should have a brass fitting and the sender protrudes through it. If its electric it should be a single wire and generally a 90* boot type connector. You'll just have to get the sender.
Sometimes you have to get a fitting that installs into the intake and it reduces the size so that the fitting with your sender will work. You can get them from Summit, local parts store or sometimes Lowes/Home depot. You'll probably have some coolant come out when you pull the fitting so Id drain a little from you rad first so as not to make a mess. Cool thing is you can then refill slowly with the sender out and stop just before the coolant starts coming out; that way you already have most of the air out of the system. Use pipe dope or teflon tape on the threads of the sender.
Ive never seen anything down on the pass. side?
Also, the one on top of the t stat isnt ideal because it won't really show actual coolant temp unless the tstat is open.
The one on the front of the intake toward drivers side is the best bet.
EDIT: so I just went and looked at mine which I just pulled and the pass. side is up against the wall
I actually don't have the spot on the intake I spoke about previously and I don't even remember unhooking my temp sender. Can you post a picture of the spot on the pass. side? Usually they'll be in the cylinder head if its not in the intake.
