I did not update the other nodes, no. Our current setup is 5 data nodes, 3 dedicated masters, kibana, and 3 client nodes. I checked the yml file on the master and it has no references to the data nodes, just the masters.
I just got done setting up a new one, I used the same version that the other data nodes are using and I copied the yml file from one of the existing data nodes just modifying the node name to reflect the name of the new server.
After starting it up, I got some errors in the cluster log. First, it failed to send the ping because the handshake failed with one of the master nodes. Said it was missing the authentication token.
I did some internet searching and decided it was because I didn't have x-pack installed on the new node, so I installed the appropriate version to match what was there already and tried starting it again. This time, the service started up fine and stayed running but the cluster log is saying that the monitoring execution failed, the exception was when closing export bulk.
That's where I'm at right now.