I'm replacing the stock stereo with a pioneer deck and I'm trying to figure out how to get the old one out. I'm not all that great at this stuff and am not sure if I have to take apart the whole dash or just take off the trim and the two bolts I can see.

Your pieces holding around the radio will just pop off, just get a flat head screw driving at the edges and pop off the woodgrain pieces off, or whatever color the holding bracket around your radio and steriing column is. Then there are just 2 bolts holding your radio in, which are located to the right and left of the radio. Make sure you have an extension for your antena, and a pro fit package you can purchase from any radio store for a 89 pontiac bonneville. I've installed hundreds of stereos, and the bonneville looked at first to be a challenging one, but once I popped off the plastic pieces covering pieces of the radio, it took me about 15 minutes to install. It's actually one of the easiest radio's I've had to install. good luck.