The external amp that drove the speakers would be disconnected if you put in any aftermarket head unit. You could tap into the factory amp if you used a Y-adapter fer the power/preamp wires. Not sure on the pinout but it could be done.

If you remove the center cover near the transmission hump, you should see if it's still in there or if the previous owner removed it. If it's gone, then yer probably better off hooking up yer own amp or gitting one from a parts yard. <img src="/forums/images/graemlins/smile.gif" alt="" />

1998 T-100 Xtra cab SR5 2WD Auto; Roadmaster Active Suspension; Yokohama Geolander HT-S; lowered air dam; full belly pan; 4? diffuser; 11" side skirts; dual transmission coolers; 67% grill blocked; Auto-RX'd; ScanGauge II/Ultra-Gauge