brake fluid change

[SkeksisNV]

Today I decided to bleed the brakes. Its been a little squishy since I bought the truck a few months back. As I started on the rear passenger side, the fluid came out a dark, rusty or muddy brown color and seemed very watery vs oily as I swirled it around in the jar. I imagine in the trucks 40 years of existence, the fluid hasn't been changed.

What is the best way to change the brake fluid? Should I stay with Dot-3 or go with Dot-4. From what I understand, Dot-5 is silicon based and shouldn't be used. What brand fluid do you guys recommend? Is there anything else in the brake system that I should check while the fluid is drained?

Thanks for the help.