What the casting numbers tell us is that it's a 79 block (D9= 79) and the 9A10 looks like the date code (79-Jan- 10). Do you have the truck to go with it?-your door tag will have the engine code on it. Is the thermostat/upper rad hose outlet located in the intake manifold or in the block? How many bolts in the valve covers?
Now THAT would be a wicked addition to an already incredible site.. Imagine a casting number decoder on the site, somewhat like the VIN decoder site that exists elsewhere on the web..
too bad i'm only good for ideas, and not programming