I recall the Lockheed Electra L188 came fitted with a weight
and CG calculator based on the actual weight acting on all 3
mains. Whether this was an airline mod or Lockheed standard
I don't know, but according to Wombats I knew (AN L188) it
picked up those rare gross loading errors that could've led to
some performance grief.
Unlike the A320 suck-squirt that only calculates GWFK in the
air (and subject to AOA error) this thing gave the direct CG &
weight before even the engines were started, AND was simple
to use.