For 1978 GMC K15 Radiator Cap 15511JNHX Standard -- Relief pressure 16 lb

1.3 Bar Thermostatic Radiator Cap 13 PSI Pressure Rating with Temperature Gauge

For 1978 GMC K15 Radiator Cap 13977RNBR Standard -- Relief pressure 16 lb

1.1 Bar Thermostatic Radiator Cap 13 PSI Pressure Rating with Temperature Gauge

1.1 Bar Thermostatic Radiator Cap 13 PSI with Pressure Rating Temperature Gauge

1.1 Bar Thermostatic Radiator Cap 13 PSI Pressure Rating with Temperature Gauge

For 1998 GMC T7500 Radiator Cap 37692QGKX Radiator Cap -- Pressure Rating 10 psi

For 1978 GMC K25 Radiator Cap 32835FJ Radiator Cap -- Pressure Rating 16 psi