I don't believe the 5" QD 5" barrel kit is any different from any Q or QD 5" barrel kit. The P22 has always had a 5" barrel/stabilizer option. The originals were P99 inspired, beginning with the Q models back in abut 2010 the shape of the slide and stabizer were changed to PPQ design themes. The barrel, barrel nut and barrel sleeve didn't change at all.
Why don't you call Ft. Smith and ask what one costs. I'm pretty sure they have them for sale. I think there are some for sale on e-bay but make sure you get a Q theme one. 1917