On a straight 8, is there a trick to removing the temp sending unit? I have the brass nut unscrewed but the bulb does not want to come out, stuck. How hard can I pull short of breaking it. Would WD-40 to area help?

PB Blaster, or wd-40 might help. Mine broke before I got it out. They get stuck in there good. Might try a pair of needle nosed pliers carefully.

I'd spray it with some kind of "penetrating oil", I wouldn't use WD-40, that's not what it's made for. Give it a good bath of the stuff and let it sit over night, at least eight hours!!!!!!!!!!!!!!!! Then I'd get a good grip with a pair of pliers, and gently pull with even force: have your radiator cap off too, that might cause a little vacuum to help keep it in; ya never know!
Good luck!
Jaybird

I bought a small inexpensive needlenose visegrips and ground it down even further to fit inside the opening and clamp down on the entire length of the projection coming out of the bulb. I gave it very slight upward and downward pressure while pulling firmly, and then rotated the position of the visegrips to exert side to side pressure while pulling. Mine came out after a few up-down and back-forth cycles. Have a pan underneath the car, because the antifreeze will start coming out. I bought a closed-end brass compression fitting from the hardware store so I could still drive the car while having the unit repaired.
Best, Chris

Pretty fragile - if you are pulling on it much it will break. Getting it out easily depends upon what you see when you look at it (after removing the nut that holds it in place) - rusty goop or clean? In my experience usually a good bit of rust has built up and slathering some Naval Jelly on, letting it sit and then flushing well with water will clean enough goop out that it can easily be extracted. Good luck.