Check my www.knus99.com
site under AM list, and go to 1310, 620 and 770 for a complete history.
Briefly, they started at 1310 in early 1978 when the City of Dallas sold the old WRR to the Mormons (Bonneville Broadcasting.) Format was initially all news (carried over from WRR) but changed by the summer to mostly AC Gold/pop oldies, with an oldies show on Saturday nights. For a short time in 1981-82, they were playing AC Gold from the Satellite Music Network, but reverted to local-based AC Gold thereafter. By early 1986, they went with "Music of Your Life" (inherited from KFJZ-870AM) and that's been the same, basic thing since...also incorporating 'big bands and great singers' along the way.
At the end of 1993, 1310 went dark when Bonneville sold it to SFX (or was it Cardinal Communications?) to make way for a sports format there (KTCK-"The Ticket," which remains there today.) After almost two years off the air, the KAAM calls reappeared on Halloween, 1995, at 620 AM (a former Wichita Falls rimshot) that was purchased by a group of 30 investors and listeners who wanted to salvage the format (and it was a long two years, as time passed with lots of publicity and broken promises for a sign-on date.)
By November, 1998, the investors sold out to ABC's Radio Disney, and KAAM was gone again (although a push was made to draw listeners over to the new KXEZ-92.1 FM, as they carried a similar format and hired some of the talent from KAAM.)
A year later, in November, 1999, Crawford Broadcasting, primarily a religious broadcaster, flipped their KPBC-770 to a 'music of your life' format and took the old KAAM calls for it. It's remained there ever since.
To my knowledge, it runs live 24-7, save for a weekend full of sponsored programming. I assume the weekend programming pays all the bills, and Crawford, being used to low-cume religious formats, is probably content with KAAM's performance. It is indeed a niche format here, drawing in a chunk of the 55+ audience, which is still coveted by some specific advertisers. But I hear of plenty of 20- and 30-somethings who listen regularly as well; many drawn in by the retro music stylings of Brian Setzer, Harry Connick Jr, etc.
Was that indeed a 'brief' history?