I have a 97 Ford F350 with the 7.3l powerstroke diesel engine.
There's oil where my radiator fluid should be.
Do I have a blown head gasket?
Highly likely it is either a blown head gasket or a cracked engine block. Check for milky gummy (lubricating) oil in engine (check under the oil cap and the dip stick). Even if the oil is fine, the fact that oil has found it's way into your radiator means pulling the head off for further inspection/repair.
With a diesel like this, it may also be a bad EGR cooler - fairly common, and a bit less work than a head. A pressure test or closer inspection should be able to confirm.
Very possible. Some ways to check: