Add a trace additive to coolant and check with UV light at exhaust. If present you have bad head gaskets. Also bad gaskets can highly pressurize rad hoses (top) to a point where you cannot squeeze them. There would also be a strong exhaust odor at the cap and even bubbling when the cap is removed. Head gaskets on a "W" motor could easily cost more than the car is worth.
1980 SWII LRL-41587C FInj
1976 SS LWB LRE-23114 Harkness RR