Go to walmart and buy a $50 car radio. Or splurge and get a nicer one. Even check out Crutchfield (do a search, they have a ton of stuff).
Almost all have 40-50w of power power channel and will not require an external amplifier.
2005 2500 Cummins/48RE/3.73, QCLB, 4wd, BigHorn, Edge Juice w/ CTS + Turbo Timer,Transgo Shift Kit ISSPro Oil and LP pressure gauges, GDP 20/2 filters, Custom Diesel Steering Box Brace
'10 Forest River Shockwave Toy Hauler 21'
Honda EU3000I Genny