Thanks for the tips. I'll be measuring what comes out and refilling as needed. I'll also be sure to check the dipstick.
True, I might try a gravity flush. The truck came from Utah so hopefully no seized nuts/bolts/screws.
Its not that the bleeders seize up. Essentially corrosion sets into the tiny output hole. So, when you turn them to the open position nothing comes out. You will know right away if that's the case though.