Will a 3 button fob work on 2 button system?
 

Like the title says: I'm looking for a replacement for my keyless entry, and found a really good deal on a three button fob, but I'm not sure if it will work with my stock two button system. Any ideas?

I don't think so. The fobs are model year specific.

I found a really good deal on a 3 button fob that said it was for a '99, which is why I asked. I have since found a comparably priced 2 button.
Thanks :)

It must have a tag and barcode on it for programming unless you only want it for the plastic parts only.

Call a dealer parts counter and give them the part number on the tag to verify it will work on your car. They will probably not volunteer the correct parts number for you. They're horses' asses that way.

Btw, used key heads that have been programmed before are worthless if they don't have the original hang tag from which the programming begins. In fact, I do not know if a previously programmed key head can be reprogrammed...