If you want to get an external task from a specific processes version you can add the processDefinitionId to the request. You can find more details in the docs.
I already tried to specify the processDefinitionId in the service REST, but the only version that returns a task is the last one.
For example, the image below show all process definition versions.
Invoking the service rest adding the processDefinitionId, you can see in the picture that the only task returned is the 4 version one, despite the fact that there are others external task, for example, in the first version of the process…