There is no block drain on a 5.0, just casting plugs as mentioned earlier. Dont pull them out, youll regret it. If you want that old coolant out so bad, disconnect the lower rad hose and the thermostat housing. Then flush it with a garden hose until its clear. Refill with distilled water and antifreeze.
Cardinal Red '88 GT 5 speed, 99 Contour Electric Dual Fans, Battery relocated, 130 amp alternator, 76mm Mass Air conversion, 75mm BBK throttle body, 5.0L .030 over, BBK SSI, AFR 185cc heads, Comp Cams XE276HR, BBK ceramic longtubes, Spec Stage II clutch, MM front/rear coil overs, MM front LCA's, MM manual brake conversion, Flaming River Manual Rack, 94-04 Cobra front brakes, 99 Cobra IRS, Torsen T2R differential, 3:55 gears