[jocko]

While I can’t recommend what grade hills to avoid parking on, I would not be willing to find out the hard way with my own truck. There is a reason GM uses the tires to prevent movement. I guess I’m a little surprised that this is one of those things that folks at least appear to be arguing in favor of (pb elim). An emerg brake IS a parking brake. It’s meant to prevent movement when parked, not for locking up the wheels when you think your other two independent brake circuits have failed. The two hydraulic brake circuits are their own backup from 67 forward. To address the valid concern over the lack of redundancy in a 60-66 braking system, the answer is to add a 67 or later dual reservoir master cylinder, just like GM chose (or was required ) to do.