Jason,

If it's a stock radio, just pop out the ashtray from above and push the
spring tabs on the sides towards the center of the radio. Then gently push it
outward. The rubber plug to the rear should just slip right out.

If it's not factory radio, it's anybody's guess. Taking the ashtray out and
peering in that hole will tell you what you need to do.

BenT
San Francisco