ScubaPro MK3 O-ring sizes?

[NAUIwowee]

I have a SP MK3 first stage that I'm using for a pony reg. SP apparently doesn't make the service kit for it anymore (kit no. 10.103.041). I can use a kit for a MK2 for most of what I need, except for the HP stem o-ring (127 amber) and the piston head o-ring (168 amber). Does anyone know what the sizes of these two o-rings are so I can pick up a couple at a hardware store?

My MK3 is a later model with the 3000 psi yoke. I'll be using it with an air filled pony, so I don't have to worry about o-rings designed for EAN.

 

[redacted]

I don't have a Mk3 but measured those o-ring sizes from the Scubapro O-ring Technical Service Schematic. The 127 is the same size as a 126 so that would make it a 2-008. It looks like they differ in material with the 127 being an amber o-ring which should be urethane. I'm sure the stem o-ring in the Mk2 kit would work just fine. The 168 measures an OD of 15/16th inches which makes it a 2-019

 

[NAUIwowee]

Thanks awap! So that means I can use the 126 that comes in the MK2 kit in place of the 127, and I just have to pick up a couple of 2-019's for future re-builds. That's easy enough!