personally i wouldn't do it - after market electronics make your truck a target for meth heads combing parking lots. Even if you get a super cheap one, they won't think twice about breaking a window and ripping it out of the dash in the middle of the day. I have put 4 after market stereos in vehicles in my lifetime, every one of them ended up getting stolen, or they tore up the vehicle trying to steal it.
if you are just itching to upgrade, upgrade the speakers under the trim where it can't be noticed visually that you have done any upgrades.
just my .02