[motto]

I once bought a WC51 that had been restored by a hot rod builder and he had used strips of teflon sheet between all the spring leaves to give a softer ride. The outcome was not what he imagined, haemorrhaged shockers leading to violent bucking on a railway level crossing that nearly threw me off the road on my way home from purchasing the vehicle. I promptly dismantled the springs to remove the teflon and found that one of the centre bolts had sheared off and another was on the way. No doubt due to the teflon.
As regards greasing leaf springs I recall reading a warning in one of the TMs that stated it was not to be done as it would lead to, 'Too lively a spring action', which is exactly what I had with the teflon in the WC51
The mystery to me is that the Dodge ambulances were fitted with greased springs wrapped in sheet metal and they were not the only vehicles to have this feature. Maybe the little difference between laden and unladen weights meant the springs could be more precisely matched to the task.
In the final analysis I would recommend you do what the TM says and nothing more.

David