thanks guys. I have driven the truck for 10 years and then on the weekend swapped the rad with a new to me (no known history one). And I thought it smelled hot, then I was watching the temp gauge, but I was thinking it is just because I'm focused on the rad, and never drove watching the temp needle before.
So I bought some prestone rad flush and have been doing the deep clean as per instructions, and tonight (day two) the needle was pretty much straight down, once in a while it would tip to the right above the zero, and then go back down.
I realize I should properly check it, but was more curious if this new rad was blocked, and now two drive cycles with the flush thinking it was blocked. There was something that looked like paper just in the filler neck, wondering if maybe there was a wasp nest inside (or still is), will finish day three, then flush it.