I searched through the forums & FAQ and didn't find the answer I was looking for. I would like to add another remote for the car. Do I need one with the same GM number (25668603), or does it have to look the same as the one I have?

I think that the GM number would suffice; I can't see them assigning the same number to two functionally-different remotes. On the other hand, I'm not sure how you could find a completely different-looking remote that would still work with your car in the first place, unless it had, say, specific buttons for controlling features that your car doesn't have; e.g. a sliding side door. (If you _do_ have that on your Bonneville, please write back and tell us how _that_ happened. )

I've found alot of remotes that look the same as mine, but are different part numbers. I just want to know if it looks the same as mine , but with a different part number, can it still be programmed to the same car ?

no you need the same FCC ID number that you already have on your remote.

Its possible to have two different part #* work on the same car.
As long as the FCC and Can #* are the same.
I did it on my SE and they both programmed perfectly.
Now I'm lookin for another FCC Kobut1bt to add a third remote.

Ebay, all day, every day
Just got two for mine, then found an original under the trap door in the console.
Also, salvage yards usually have boxes of them behind the counter. Just match the FCC #, like they said.