This was the old WJJD-1160. It was about the only other station on 1160 besides KSL. They both wound up on the same channel after NARBA. KSL was the dominant station, so WJJD had to protect KSL. Years ago (just a bit before I got here), KSL used to sign off at midnight, and WJJD could come back on until KSL's morning sign-on.
I'd have to look back in their history cards for the dates...I think they had a pip-squeak of a night-time signal once. KSL then went 24 hours with Herb Jepco's "Night Cap".
I think WJJD had a couple of different owners before Salem bought them. So, that's likely when they added the night time transmitter. At 50 KW, they needed a tight pattern and new site to protect KSL.
I'm going by 40+ years of memory on this ..details should be on the FCC History Cards under WYLL.