I thought it was an e. Ackermanni too, but the flowers are 5 inches across and 3" deep. I am not sure Ackermanni are that large. It seems there are so many that it could be it is scary. I do want to be sure it is accurately ID.

Undoubtedly. Although I don't recall that I've ever seen an Ackermanni quite as old as yours, I have no idea exactly what size the flowers could reach on such a mature specimen. It is interesting to explore. I did see that E. Ackermanni has been transferred to the Disocactus genus. They do that all the time with these plants. Drives me nutty, but it's good to be accurate.