Camry Headrest

Lime most on this forum, I drive a Prius. I've heard quite a bit of complaints about the Prius' uncomfortable seats. I have a bad neck that creates problems in my upper back and entire left arm. The doctor who is treating me for this also has a Prius , but is considering getting rid of it due to the seats. I have discovered that shedding my winter coat while driving helps, but not entirely. Furthermore, I have an '88 4Runner for snow driving. It's seats are actually much more comfortable. What's more, those seats have a nifty feature; fore/aft adjusting headrests. I tried slipping one of them into my Prius, but the headrest's poles from the 4Runner are too thin. Does anyone know if the headrests from any other more recent Toyota models have a similar feature with the same pole diameter? I already tried a local dealer, but they were less than useless. I figured it would be worth a shot...
Similarly, does anyone know if seats from another model (with side air bags) would fit the Prius? Just curious.