I used to have an F-150 with a keyless entry keypad on the door and it was by far my favorite feature on the truck.
After a quick search on ebay, I found this.
For only $30 it may be worth a shot. What do you all think?
Only one problem.. I made a habit out of locking my keys in my truck so I didn't have to carry them. It was not an issue before because the OEM Ford keypads work off the vehicle's battery where as this one is completely wireless and if the battery dies you're screwed.