I have an 88 v6 disk in front drums rear.

I was under the car looking at the floor pan and notice this wet on the drivers side where my feet would sit. I touched it and the paint came off and realized that it was brake fluid. I checked my resevoir and it was really low. I've looked at the lines and I dont' see any leaks. I never see any on the ground. I pulled the carpet back and felt under the pad, by my feet, and it was a little wet. It smelled like brake fluid. Does this mean my master cyl is leaking near the back? I have an extra one from an 89 v8 that I can put on, will this work.

Anyone have any ideas?

 

anyone?