Installing a sound system in a bench seat truck?

[SelectSeven]

So I have a '86 Isuzu Pup pickup truck, the cab is rather small and has a bench seat in it, but i'm a big music enthusiast and enjoy when a car has a good system installed, is there anyway to put a system in my truck or am i stuck with my stock speakers and no bass? Thanks for any input
Okay, this really wasn't looking for a response from a smart ass, older cars are classic, and quite frankly it's annoying when people rant about buying a new car.