Well on a small block Chevy there will be no coil wire going from the top of the cap to a coil. What you can do to see the difference is go here.
HEI stands for High Energy Ignition.
all 1984's had HEI ignition.
High Energy Ignition (HEI) Module.
small block Chevrolet with HEI ignition is 45
HEI means High energy ignition SYSTEM
inside the distributor
HEI was an ignition system used on Chevrolet and GM vehicles.
If it's still factory it will have an HEI ignition system.
The wires are different - HEI ignition wires won't work in a standard distributor - they all go in the same relative places though.
12 or 13 degrees
1.8.4.3.6.5.7.2
HEI ignition system? Inside the distributor cap (top)