Replacement for 103H7123-5040

I support several machines using this stepper but it seems to be no longer available. The newest machines come in with a RTA model vm 2KIE stepper which I think is just another sanyokenki but not in their system.
I need to order more spares. I have used the 103H7123-5840 in place of the -5040 but am not sure if it is the best alternative. Can you suggest the closest match the -5040

There is no suggested cross, so make sure the specs on part 2300-103H7123-5840-ND
, as I I do not find any direct matching part.