Originally it would have had DexCool.
r-134A
It uses Dexcool.
The original coolant would have been "DexCool". The cooling system should be flushed and coolant replaced every 5 years or 100K miles if you use DexCool.
Dexcool
Dex-cool.
Dex-cool it is orange-red incolor
low beam headlight bulb type: 9006
If the Blazer is gasoline powered the antifreeze can be any kind that is for sale for gasoline powered vehicles.
dextron mercron
Dot 3 will be just fine.
A NAPA 1040 or the NAPA 1036 will do.
dex-coo 50/50