[TJ's GMC]

Hi guys, what's the normal operating temp for a 67 305E? The 60-61 shop manual states 160 degrees for a 305A. Did that change? Been having funny readings from my gauge. As you all know I did a light rebuild on the engine and during that I installed a new Temp sending unit from Napa. Ever since then the temps seem to act funny on the gauge. Normally the engine runs just below Normal. And when it Did run at Normal I was towing 10,000 pounds and sometimes it would go just a tad past. When you'd pop the hood you could feel the motor was Hot...maybe around 190 degrees. This was before the rebuild....now after..and with the new sending unit...it stays around 1/4 to just below norm most of the time...but if I let the truck sit for let's say 1 hour...and go to drive...while driving the gauge goes to norm...and just slowly keeps climbing....until it reaches the 3/4 mark. And this happened today, warmed up the truck for about 5 minutes at a 800 rpm idle. Bank is about 3 miles away...made it there and motor was at 1/4 temp. Truck sat for about 10 minutes. Fire it up and heading back home I'm watching the gauge just keep climbing...especially under acceleration. Speed on home, pop the hood and to my surprise....the motor isn't even that Hot! I could still easily hold onto the top rad hose without getting burned. Could almost hold onto the thermostat housing to. So I have ruled out that the motor isn't actually Over heating. Maybe it's the thermostat? Faulty new sending unit? Dunno guys, what do you think? What was the rating for the stock t-stat?