What dougrainer said is spot on. But it probably is a Chevy P30 chassis. Easiest is to make sure parking brake is completely back. Release it and at the same time pull pedal back to see if brake light goes out. To check fluid level, you will probably have to pull dog house off and look under floor on drivers side. Difficult to get at but can be done. If fluid is low, be sure to check front brake pads because as they wear caliper fluid volume increases. Otherwise, you should look for a cause for pressure imbalance between the front and rear brakes.