I just put in a Panasonic head unit and some Infinity Kappa 4" in the rear deck. It's not as classic looking as the Nak but is about the "plainest" looking head unit I could find locally. The Kappa's almost drop right in but do require a little drilling.

Sounds Ok, not much bass but what do you expect from 4" speakers. Decent sound and cheap enough that I won't cry when it gets ripped off.