28 pin IC, it says on it "6 17 A1 DM" then on the line below "DELCO466" and in big letters "164".  Probably some digital thing?

Is this for an automotive product?

Quite possibly could be the EPROM containing the program for the microprocessor on the board (assuming there is one).

Actually, it's from a car radio.

Delco makes automotive stuff, or at least ACDelco does. Parts, sports kits, custom bits for race teams, but not radios I think.
then there's Delco/Remy, starter motors and such, again no radios. They do carry all kinds of electronic monitoring tools though. The name crops up a LOT at tuning specialists.
It's probably a custom-order chip that either does scanning or text messaging, or a pre-programmed (E)Eprom.
Doubt it's a useful chip for effects.

Delco = Deleware Engineering Laboratory Corporation

They OEM all kinds of vehicle parts from everywhere to everywhere. I would be surprised if they actually built the silicon since that's almost certianly done in Asia, but chances are good that they designed it or at least customized an existing part.

It's pretty hard to get specs on delco sub-components, and very very hard to get replacements. Sometimes, there will be an off the shelf part that works and they'll just stamp a delco part number on it, so for parts like amplifiers you *MIGHT* get lucky if you look at other data sheets and find the original part, but you'll have to keep your fingers and toes crossed. I'm guessing your 28 pin chip is a chunck of radio receiver or a microcontroller. It could be analog, digital, I.F., or very likely a combination of all three.

-Peter