Dolphin Shower 860

Unfortunately there is nothing that is a direct swap.

However....... Triton has recently brought out the T80Z this shower has been designed round being a retrofit unit  (Tritons word not mine!)

The pipe work can be brought in from almost any position and there is a reasonable amount of space for cable entry from most positions.

Here is the link.

http://www.showerdoc.com/new-showers/triton/electric-showers/ZTRITO-SP8008ZUFIT-Triton-T80Z---8-5kW-(White-Chrome)

See Video at the foot of the page

I personally would go for the T80 Z before the Topaz there is a fair bit of electronics in the Topaz and we sell more spares for the topaz than we do for the T80Z