How may I select 84 hours of GFS data at 3 hour intervals?

[Rhino1618]

Hi,

I am trying to obtain 84 hours of GFS t2m forecast data from 1 run at 3 hour intervals.
I tried following the HRRR example from the FastHerbie page, but I'm slightly confused by it. I get the example is trying to get 3 hours from 3 runs, but I only want data from 1 run. How would I format that request?

Thanks,
-Rhino16