The bushing is that par tthat some might refer to as a bearing. It is a cylindrical or spherical support for the motor shaft, in this case made of a porpus copper/bronze like material. There is one at each end of the motor shaft.

When looking at the heater after removing the centre console (radio, heater controls, switches etc. look from the location of the handbrake lever, towards the firewall. The heater is beige or grey plastic. The centre barrel (lying on its side) shaped portion is about 10" in diameter and 9" long. Drill holes at right and left end of the centre barrel I described. On the right and left ends of the barrel are larger diameter 'doughnuts' of the same plastic material. Drill the barrel close to these 'doughniuts'.

There is a model of heater that is different. This one has thumbwheel controls rather than the vacuum operated system that has 3 pushbuttons and a slide lever for temp. The above description does not apply to this heater.