thanks for the replies! I really appreciate the pix. I forgot to mention in the first post that I have a screwy fuel gauge too (dual tanks, doesnt seem to read accurate on either), and there's an electrical gremlin in the tach when I turn on the headlights (at idle it reads 0 rpm). I'm pretty sure either there is a bad connection/ground somewhere or someone messed with the wiring at some point and crosswired something. Going to check the sensors today and see what's up.

As far as the red coolant, I'll keep a close eye on it. I dont drive the truck right now because my utlility bed isnt tied into the frame and I need to do rear brake work. I've been having trouble finding "diesel" coolant, and came across this stuff at Tractor Supply. It says its supposed to work with everything and is specifically made for diesels, but if I can find some green stuff (dealer I guess) I'll flush and swap it out before I drive it regularly.