Does a 1991 V6 4.3L require Dexcool?

[KAHruzer]

In the cooling system.Just getting around to flushing and refilling with coolant.There was none in the water at all, just lots of rust.I'd like to avoid Dexcool, if possible.I think this engine has steel heads, so shouldn't be a problem with the green stuff, right?

[KAHruzer]

btw, my radiator drain plug is at the lower back drivers' side corner of the radiator.
No tube, just a thumb turn screw. As such, when opened, it runs out directly down onto
to the rad support frame cross member below, then runs the channel and drains out every hole across the front.

Is this normal and just bad design, or am I missing something here?

Didn't start with enough drip pans for the job.