For what its worth, I had the rear passenger side line on my '64 C60 fail with roughly 4ton on the bed (4.5ton curb weight truck) coming into a downhill T intersection with trees on the backside and moving 48mph. I bailed left over a small ditch into an empty field while holding that E-brake for dear life. It brought all 17000lbs to a hard stop in just a little over 120 foot. It threw the drum out of round, roasted the pads, sent me into the roof, bounced me off the dash, and dropped me on the passenger side of the cab, but it did its job.
That little brake may not seem like much, but its pretty mighty.
