[Gnarly Old Dog]

The RTR shock caps are completely interchangeable with the standard TLR 22 alloy ones or the alloy ones with the bleeder valves. The 22 series of shocks are referred to as 12mm which is the internal bore of the shock - not the outer or inner/outer diameter of the springs. The TLR 8ight 2.0 had 15mm shocks and the new 8ight 3.0 series has 16mm - that's where the 12mm / 16mm confusion is likely to be coming from.

Here's some part numbers that might come in handy

TLR5065 - Alloy Caps with Bleeder Valves + Screws (Pair)
TLR5074 - Low Friction Black O-Rings (8)
TLR5093 - Standard (grey) O-Rings (8)
LOSA5006 - RTR (Plastic) shock caps with Bleeder Valves (set of 4)
TLR334000 - O-Rings for Bleeder Shock Caps

Springs
TLR5172 - TLR5177 22 Buggy Front Springs (Red / Orange / Silver / Green / Blue / Black)
TLR5165 - TLR5171 22 Buggy Rear Springs (Grey / White / Yellow / Pink / Red / Orange / Silver)

You should be aware that the standard TLR22 kit shocks use a diaphragm in them at the top of the oil / inside the cap and as such, once the cap is fitted, they need no further o-ring sealing.

The RTR 22 comes with the plastic caps with bleeder valves that make shock bleeding much easier. This makes the shocks emulsive in action (a mix of air + oil) whereas the diaphragms keep the air out but make the shock more tricky to bleed consistently. The emulsive style caps require sealing either with the included O-ring with the plastic RTR caps or, if you use the alloy bleeder valve caps, you can use the external o-ring TLR334000 that fits over the shock cap threads on the shock body and which is compressed by the cap once it is screwed on.

As for O-rings, the standard shocks are fitted with 2x grey O-rings which provide a long-lasting shock with minimal oil weepage. The downside is increased shock stiction (the initial friction of the shaft moving past the o-ring). This makes the shock less active and many racers will prefer the action of the shocks with low-friction O-rings but these require more regular maintenance. Some racers will fit one grey and one black O-ring to achieve a sort of best of both worlds.

If you are refreshing your shocks for the first time, you may notice that the TiNi coating is scratched or worn from the shock shaft (mainly on the rears). It is worth refreshing the shafts at the same time as the seals for that super plush feel. You can always keep the old ones for emergency spares. TLR5087 and TLR5088 are the part numbers for the buggy Front and Rear shock shafts. Both come as pairs.

HTH.