@BrianDonnan Kindly refer to the following documentation for NX-3060-G5 system specifications - https://portal.nutanix.com/page/documents/details?targetId=System-Specs-G5-Multinode:sys-system-specs-nx3060g5-r.html
Also, as mentioned by @JamesDyke earlier, as per the naming terminology for NX Hardware https://portal.nutanix.com/page/documents/details?targetId=System-Specs-G5-Multinode:System-Specs-G5-Multinode, the naming convention for NX-3060-G5 HW model is NX-3X60-G5 where X is the number of nodes present in the block. If your case, since you have 3 nodes, it will be NX-3360-G5
Also, the only difference between 3-nodes and 4-nodes in the NX-3060-G5 HW model is that the last node slot (located in position D) should be empty. Kindly refer to the NX-3060-G5 Node Naming guide for more details on this one.
Regarding the replacement model number for this node, it will be NX-3060-G5 hardware model node. If this Nutanix asset has a valid support contract, then it will be available for replacement in case you have any node hardware failures which need a replacement. If this happens, then please contact Nutanix Support and we should be able to help you out in creating a dispatch for this node replacement.
Kindly let me know if you have any more questions on this one.