EY wrote on Jul 4^th, 2021 at 5:09pm:

In the 737-300 you can't turn on both FD at the same time.

That's not true, you can use both Flight Directors in the B733. I'd highly invest in purchasing the ITVV Boeing 737-300 (check below) and having a watch. Both FD's are set on for departure and shown on the PFDs as well.

https://www.itvv.com/civil-aviation-on-demand/ppv/instant-flight-deck-streaming-documentary/boeing-b737-300-5028940040219.htm