Can anyone give me a short overview of this place? It started out as a TLM haven but the original founder died and it was taken over by novus ordo types? What about now? I hear it is again a TLM haven. 

You can hear much about the history of the Abbey from one of the monks who lived there at Restoration Radio:

https://www.truerestoration.org/season-ii-the-spiritual-life-episode-0-introduction-show/

Apparantly Fr. Leonard failed to mention that they were really sedevacantist. 

I was a kid and got the privilege of meeting and having dinner with Fr. Leonard. I remember when the abbey in Cullman was still under construction.  It's sad to know the story.  [....] posted a sign that the abbey was closed for Mass. I suppose they were 'ordained' in the New Rite and started offering the Novus Ordo some time later.  The parishioners regrouped near Huntsville and recieve a priest from the CMRI nowadays.

I claim no special knowledge of the story[†], but perhaps you know it so well that without intending to, you overlooked points that ought to be stated explicitly (if accurate):

The chronological order was not that the abbey was constructed, its chapel was consecrated, some Catholics in Alabama eventually discovered that the new abbey was celebrating the traditional Latin Mass, and then traditional Catholics within a tolerable commuting distance became parishoners, was it?

Wouldn't it be more accurate to write that some Catholics in Alabama discovered the traditional Latin Mass being celebrated by the clergy that would eventually reside in Cullman, became de facto parishoners, and for that reason, donated the bulk of the money used to construct the abbey, to which they lost access for the traditional Mass & sacraments after the prolonged illness and death of the de facto abbot (who I assume is the aforementioned Fr. Leonard), because his death made possible a Novus Ordo coup by relatively newly arrived opportunistic young clergy who knew perfectly well what a subversive act of disloyalty and disenfranchisement they were committing.

So as I recall what I've read, those parishioners who regrouped have already paid quite recently to build a site in which to attend the traditional Latin Mass and receive the traditional sacraments: Christ the King Abbey in Cullman.

Please correct me if I misunderstood the story[‡] and if this reply is mistaken on facts or draws invalid conclusions.

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Note †: A search for "Cullman" & "Leonard" focused on <http://www.traditio.com/> (via the input slot for "advanced search" that's marked "At this Web site or domain:") might suffice. But I don't know if their version of the story might indulge in biases that reduce its accuracy.

Note ‡: The story is really infuriating, even to myself, despite not being personally affected.  So maybe I indulged in waaay too much bold-face formatting.

Does this mean the Abbey is under the diocese? It's now affiliated with Una Voce?
http://unavocenorthernalabama.com/parishes/

Yes. After the death of Fr. Leonard there was a reconciliation with the diocese of Birmingham. Part of the issue was that Fr. Leonard had failed to tell them that they were a sedevantist organization.  

This is odd because I know of three current priests (at least one was ordained while at the abbey) who are sedevacantist and two of them (I have not met the third) claim that the Abbot was indeed a sedevacantist himself but believed that the issue was divisive and would not make any public statement.  Sedevacantism was not a requirement at the Abbey nor was it really an issue to be discussed.

I understood that Fr. Leonard and Fr. LeBLanc of Our lady of the Sun, would phone each other.  Fr. LeBlanc being independent, was not sedevacantist at that time, but Fr. LeBlanc did accept the Sedevacantist position months before he died in 2006.  

I understood at that time that Fr. Leonard had no position, and I also understood, he had a priest (?) with him for 20 years and he was the one who took over the Abbey to New Order when Fr. Leonard died.  I pictured this New Order priest was a silent infiltrator.  To bad.

I understood at that time that Fr. Leonard had no position, and I also understood, he had a priest (?) with him for 20 years and he was the one who took over the Abbey to New Order when Fr. Leonard died.  I pictured this New Order priest was a silent infiltrator.  To bad.

The abbey quickly made a deal with the diocese after Fr Leonard died.  Infiltration would be the only explanation.