They did have them though, along with cut conns:
USS S-42 SS 153 photographed from the deck of a neighbouring sub.
Dutch Harbor, Alaska 1943. Notice the sea and air search radars installed on these older boats.
from
http://pigboats.com/subs/s-boats4.html
Remember, the deck gun was bow-only, in case you think you are looking forward there... lol - I was reading about the first one to get the SJ was in the South Pacific (Noumea??) in late 1942, but I cannot find the article. It was one of the Asiatic / Brisbane boats though... I can't remember the SD install, but Fremantle comes to mind... maybe...