Havent seen any posts on this, but I picked up a Sony MEX BT2600 deck the other day. Havent installed yet, but no one has mentioned aftermarket decks affecting the power antenna. Still works right? Shut the car/deck off and it still retracts?

Also, anyone have, or know where I can get a dash kit that doesnt stick out an inch from the dash?

if you buy a harness adapter, you will be fine. DO NOT cut the existing factory harness.

No, I went the crutchfield route, I have the wiring harness and stuff. I've installed a few decks in my time. I've just never dealt with a car with a power antenna before.
I'd still like to find a flush mount kit tho. Hate the idea of it sticking out...Whatever. LOL

There are some flush mount kits, you kind of have to hunt for them, actually I built mine out of a multi car dash kit which covered tons of different models (it was actually a kit my friend bought and didn't need anymore so it was free for me ), it was a metra kit, and basically you had to put it together like a lego kit and attach the pieces you need, and it came with flush, bubbled out, and some crazy other stuff I have no clue how it could be used, but there are kits out there. Power antenna should be fine, I'm not sure if 96 is like this but in my 94 I needed an antenna plug converter from mini size to full size, because the stock gm deck took a mini plug. If you went through crutchfield they should have sent it if needed.

GM multi kit from metra is a 99-4544 should be in a red bag... power antenna will be a lead off the plug that goes into the radio. it will be up ONLy when fm radio is on, im at work right now in the breakroom when i go out back to the shop again ill get ya the exact flush kit number (which should be a 4544) and the wire you need to hook up for power ant

If i remember correctly the 454 kit is a universal you assemble yourself. Best Kits has the same thing but they call it a GM 4. You will also need an antenna adaptor, and a wiring plug. Check the plug that came with your sony deck. If it has a SOLID BLUE wire in it then that is your power antenna. (some decks, such as my pioneer 7600 do not have a power antenna wire.) You just match up the colours of the sony plug to the harness adaptor.
Solder and tape/shrink tube is your best option for connecting the wires. You can also use butt connectors if you have them available. If you absolutely must do it the ghetto way, then twist the wires together REALLY WELL and tape them individually very carefully. Also it would be a good idea to tape the antenna adaptor onto the cars antenna lead because they sometimes have a tendency to slip off.
I am not sure about your car, but some GMs have pieces of plastic and metal behind the radio that make the deck stick out (due to the aftermarket deck being deeper then the original unit) therefore making flush mounting impossible, unless you remove the obstruction. Use an air saw or something similar to remove he bracing behind the radio if necessary.