Though it might be possible that the engine was pulled out of a 1975 Ford Granada at sometime, it didn't originate there. C8DE-6015-B decodes as fallows.
C = Decade of 1960
8 = year so a 1968 still not the exact year though
D = is the Ford Car Line the part was originally designed for in this case a Falcon, but again these engines were also used in many other Models too.
E = Ford Department that ordered the part to be made this is the Engine Department
6015 = This is Fords Generic Number for a Cylinder Block
B = Means that this part was redesigned a number of 2 times
I can't tell you the Ford or Mercury Car Model (Falcon, Fairlane, Mustang, Comet, to name a few) that the engine could of originally been installed in, only that it might be from a 1968 to maybe a 1970 year engine (my best guess is a 1969) which of course rules out it ever being from a 1975 Granada. To get the exact year, month, and day that Block was cast at the Ford Engine Foundry you will need to find the Date Code it will have 2 or 3 numbers and a letter it looks like a small metal tag with a straight blade screw head on each end see example below. With some more and better pictures of the engine details I or another site member could probably tell you the engine size also.