I am looking to get the OS 21RG-X (P) or the OS 21RZ-R(P) for my Tmaxx .21 conversion and am having difficulty with the sites details. Does the (P) indicate that it is a Pull start or Pilot shaft? I know that the RG-X can have a pullstart, but what about the RZ-R. Also looking at the OS 21RZ-V01B it says it has a optional Pilot shaft, but there are no pictures to show how exactly the pilot shaft is used. I mean is the booster still used in conjunction with the pilot shaft or do you have to sacrafice the booster for the pilot. Sorry but I am new to the sport and just need to make sure of what I am getting before I order. Thanks for any info you can provide...