how can you tell if you have a blown head casket

Check to see if there is a milky substance in your oil, deposits on the spark plugs, compression check on cylinders, problems with your heater, weird smell from the exhaust, loss of coolant. All of these can be signs of a bad head gasket

Normally you will either see oil in ur anti-freeze or you will see anti freeze in your oil. that year neon was notorius for that.

The body in the casket will not have a head.