I feel dumb now, but I forgot how it goes back on. I took it out to get the car painted, & that was more than 4 months ago.
it will help me tons to see a diagram.

How about this from techinfo?
http://www.bonnevilleclub.com/forum/...=article&k=105

Thanks, but what I need is the oval one under the spoiler & in the middle of the trunck.

I am not at home but I believe it takes an 11mm socket and the assembly pulls back into the trunk. Be careful with the plastic tabs so you do not break one off. If you have a trunk liner that will have to be partially removed to get at the third break light.

http://www.alldatadiy.com/alldata/AF...68199/34868216

OK - now that there is a better description - try this...
HIGH MOUNTED STOP LAMP REPLACEMENT

Ok, now lets say I broke one of the plastic tabs. what do I do?

Give up and ship that Car to Canada

I'll trade ya

Does some one knows if there is a way to fix a broken tab. Or if I can install it like it is.

You can try and see if some glue like epoxy or JB Kwik might hold it, if you're lucky. Otherwise, install it and see if you end up with any water leaks, which will likely be the biggest concern.