The DC power supply is the top of the two metal boxes. It's the same formfactor as a PC supply (and may in fact be one with a different connector on it). These can be bough from e.g. Happ in this formfactor with the "standard" 9 pin connector.
The bottom box is unknown. It probably has a fuse block and distribution block in it. There may be an isolation transformer hidden in there, too.
Blitz was often shipped with a WG U5000 which would not have required an isolation transformer, so it's possible that this cabinet doesn't have one.