John,
The evolution of weighing is quite interesting.
When I was a lad ( a few years ago now!) weighing was done with your glorifed bathroom scales.
Then came the magic of load cells
Most people changed to this. I have seen a couple of nasty accidents where the aircraft tipped and shot the load cell out like a bullet ! and also a jack through the wing.
If you have been involved with weighing aircraft for any length of time you may remember Ken from Aviation Traders who used to come round with his station wagon and perform his load cell magic before your very eyes.
The last few large transport aircraft I have been involved with weighing have gone back to bathroom scales !
The full circle !
PS the FAA TCDS usually shows the levelling method