I'm curious to know the specifications of my central air conditioner -
size, efficiency, etc. The labels on the condenser unit have all
faded beyond recognition except for the brand label - "RUUD High
Efficiency". The furnace is a 1969 Chrysler Airtemp 150k BTU forced
air oil burner and for all I know this could be the original air
conditioner.

It seems to work fine but knowing more about it would help in
determining when to replace it. Any thoughts how I might figure that
out?

Thanks!