My understanding is they don't make 5100s for the 3rd gen 4runner but rather 5100s for Tundras and Tacomas. I am running 5100s for 1st Gen Tundra (00-06) with Tundra TRD coils. I believe you can also run the Tacoma on the 4runner with the TRD but I was told that they don't feel as "solid" if you will.
Don't quote me on this because I am not 100% sure on any of this besides what I am running.