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...

The O.S. nomenclature for pull-start engines has an "X" as the designator. A "(P)" means the engine is equipmmed with a pilot-shaft type of crankshaft.

The pilot shaft is the way to retain the clutch/flywheel assembly, and has nothing to do with a recoil starter. European R/C cars tend to use the pilot shaft crank, as to a few of the Japanese R/C cars.

The O.S. Max RZ-series cannot be converted to recoil starting.

The .21 RZ has two versions, pilot shaft and non:

OSMG2065 13860 .21 RZ-V01B
OSMG2066 13861 .21 RZ-V01B (P)

Thanks alot, Bax for the info, that cleared up my misconception about the Pilot shaft. I have purchased the OS 21RG-X(P) and look forward to getting it setup for my Tmaxx conversion.