If you want to model the LM in flight you will need to install the landing probe. The Shapeways part provides you with 4 landing probes as there was one landing probe under each landing pad for Apollo 9 and 10. As the landing probe on the +Z pad could possibly obstruct the way for the astronaut to reach the lunar surface, it was decided to remove it, so for every LM from Apollo 11 to Apollo 17 the landing probe is missing on the +Z landing pad (landing gear with the ladder).

That decision was taken at a very late stage, for that reason the probe locking mechanism is still present on the +Z primary strut on Apollo 11 and 12. It disappears from the +Z primary strut from Apollo 13 to Apoll o17. If you intend to model one of these late LMs, make sure to remove that part with a precision knife.