Connect two shafts with minimum distance between shaft ends (DBSE) may be problematic if you want to use a torsionally rigid disc coupling.
The available distance does not allow inserting a spacer between the shafts. The spacer is required to allow the installation of two plates packs that can absorb a parallel (radial) misalignment. In fact, with only one plates group, only axial and angular deviations can be compensated.
Many manufacturers have designed couplings, with a special design, can fit two packs, thus ensuring full flexibility of the system. Most of these construction forms do not, however, replace the plates without disassembling or removing the connected machinery.