While Driving the engine began to clatter then very quickly locked up. It would not crank over, we trailored it home and once off the trailer and cooled down, it turned over fine. Started the next day and ran fine. Any Thoughts?

You probably scored the cylinders and collapsed the pistons. If the engine has knocks it didn't have before, or if it uses excessive oil, that would be a sign of damage. If it still runs quietly, and seems smooth drive it. If otherwise, a teardown and inspection is in order.
Norm

Any water in the radiator? If it did it once it will do it again. Take it down before it destroys itself.

Greg
We need more history on your car. Typically it either had to get really hot (low on water), OR it had to be low on oil, OR the pistons could be fitted too tight. Either of these three could cause your symptoms.

The antifreeze level is up, it did not over heat. The thermometer works, and it did not indicate that it was hot. Oil level is fine, altho I am running a ten weight non detergent, it calls for a thirty. I use the ten because with the thirty it is too hard to crank. Pistons arent too tight, its been in the family and never been rebuilt in the last ten years or so... any other thoughts? thanks for any help.

To overcome the hard cranking, leave the emergency brake handle ahead when it is stopped. That will squeeze the oil from between the clutch plates, and make it easy to crank with the heavier oil. 10W is a little light, although I use 10w-30.
Bob

Greg
In this 10 year period how much has the car been driven (about how many miles)? How long since the last oil change? It really sounds like a piston "scuffing" problem. If the oil is badly "diluted" with either gasoline or coolant your symptoms would occur. Maybe you are leaking coolant (antifreeze) into tthe oil. It will tend to turn milky if this occurs. If it was a particularily hot day and/or you were pulling a long hard grade pistons will expand enough to scuff onto the cylinders. When the engine cools down it will start right up and not sound much the worse.

Greg, I had a similar problem with my '22 one ton. Turns out when the engine was rebuilt the the rods were too tight...engine ran fine... would start to knock...loose power would lug down till it would sieze. My cure was to let it cool, pour a can of STP in the engine and away I would go.

I finally took off the inspection cover and discovered the problem. I was able to scrape the bearing (#1) and refit it to the crank. No scores no costly damage. problem was over. That was in 1975 she still runs well.

John