To get back to the original topic I must get a set of those bits.
Dave, we have had some water get into the ECU box and drip through the cable grommet. It may be well worth while putting a thin neoprene gasket on the firewall side of the box and the base nearest the heater box. The bottom edge and side are probably best left so that any water that does get in can get out and leaving a bit of air circulation for drying.
At the moment I have a tube going from the lower drain of the heater box and down near the gearbox, and some 100 mph tape on the top edge (firewall side)of the ECU box. That seems to have stopped the water ingress which was mainly noticable from the aircon condensation coming out of the heater box drain.