What should I do, get a used or rebuilt, motor? Or have this motor rebuilt?

It's'04 ,6.0 Power stroke, v-8 turbo diesel. And yes it was losing coolant, profusely, out exhaust pipe!!!! But amazingly it ran great, just couldn't keep coolant in it. But never over heated! And he said something about bent push rod too! And coolant getting in the oil, which wasn't when I took it in, after he let it run for a while while he did his diagnostics.

Ask to see bad parts.. That shouldn't be a problem.. *Mechanic* should be glad to show & tell...with full explanation why engine is shot! .. Without actually being there... inspecting the engine and failed parts, not much we can help with.