Coolant drain on block on 250/4.1?

[C10wip]

The coolant in my newly acquired truck looks like mud, the water pump is shot, the radiator is plugged and the heater doesn't heat, so I'm replacing the radiator, heater core, water pump, thermostat, hoses etc. I drained the radiator and took the lower hose off but only got about 6 - 7 quarts of "coolant" out. I'm going to flush it but want to drain all of the the flush water as well.
My question - on a 1980 250 L6, is there a coolant drain on the block, or will all of the coolant dump out when I take the water pump off? I have the shop manual but it does not seem to show a plug.

Thanks.

[78maliburat]

Pull thermostat out bolt housing back on put a water hose down the neck and turn on water let the water run and the water will come back out the top run until clear ...... When youre satisfied pull bottom hose and flush out .......since the bottom hose is off put hose in rad and flush too

[D13]

No drains on the block. If you have the water pump out you can try flushing thru the thermostat neck. If it's really sludged up, you can pull the core plug (round plug on the side of the block), furthest toward the rear. Just be sure you have everything dry when you install the new one. Not a bad idea to use the brass ones with a little wipe of sealer.

[C10wip]

Thanks, that explains why I couldn't find it. So, I pulled the thermostat as suggested and flushed through the heater hose lines - turns out the PO had thoughtfully already removed the thermostat, which might have been part of the issue with no heat.
The other odd thing was the thermostat bolts and lower housing - they were packed solid with crap, so I started to run a tap through the housing - started to get a little too much resistance so I checked the bolt and they're 3/8-16, so I'm guessing it had an older pre-metric lower housing put on at some point.
Anyways, got it flushed clean now - thanks for the help.