Well, after much head scratching and shoulder shrugging, I have my answer. I ran out, picked up a laser temp gauge to put a temp on the block after running 45 minutes in traffic. Gauge in Truck shows 105. Grounded the wire to the block, shows pegged hot...not a gauge or wiring problem...thank goodness! (I hate electrical probs!) Point the laser at the cylinder head...low and behold, 193*. Okay...Thermostat is working dead on. I ran hard, and I ran normal. Floored it, left plenty of tire behind, and also tried to drive very conservatively. Laser shows the same +/- 4*. Okay...Here I am thinking that I got a bad batch of thermostats, and now my thinking is that after three new sending units...all same store...I actually had a bad batch of sending units. I go to different store, try a different brand, change out the TSU, and Voila...Gauge in the truck shows exactly the same as the laser...spot on. Rises up about 10 degrees if I drive hard, and comes right back down. I probably could have told by the temp coming out of the vents...but just to make things difficult, well, the blower switch went out just before this happened, and I just don't feel like taking the dash apart yet to fix it! So...I appologize for racking everyone elses brains and all, but who would have ever thought! No me, obviously. Thanks though for all the great advise, there is no doubt about the knowledge base here. Have a great time with your projects, and look back to this post soon. (This week) I will post a link to a youtube video with this neck snapping 84 chevy! Long Live Bowties!