a socket for a bulb should plug that hole up. In my truck I got a tail light harness from a 96 ranger and it has the wiring for a three bulb set up. There is a plug in on the frame at the rear of the truck where you can unplug your current harness and put one configured for three bulbs. This will give you a separate bulb for blinkers. You should be able to pick one up at a j/y cheap, but if you don't want to then you can put a socket in the spot.
01 Maroon Ranger XLT Supercab 4x4 4.0L Sunroof
Mods- K&N Cold Air Intake - 3 Bulb Tails - 06 Corners- 60/40 Seat Mod - Explorer Shorty Center Console - Explorer Overhead Console - AutoDim Mirror - Fog Light Mod - Blinker Mod -Turn Signal Mirrors - 06 Badges - Whelen Edge Lightbar -Yaseau FT 2800m - Front Mount Receiver - EATC- Homelink Visors