The traction motors and pantographs had to be modified for the higher voltage.
Although Zagreb Workshop showed, that it could do the job, the real full re-electrification of Zagreb-Rijeka line has not happened yet.
Croatian Railways do today rent multi-system locomotives in order to drive the whole line non-stop.
A power conversion on the total line is slated to be finished soon.
Probably, newer and more modern locomotives will be purchased to serve Zagreb-Rijeka line.