Only Level D sims will have the capability and necessity to replicate full control loading and aerodynamic characteristics.
It’s not only level D machines that have full Control Loading and the aerodynamic characteristics. Level C as well as Level B use them as well (the ones I’ve worked on anyway)
All modern Simulators (and old) have to have the characteristics of the Controls checked as well how they handle
Control Loading feedback nowadays can be either hydraulically or electrically driven. Older machines (really old ones) had springs or rubber bungies fitted!
The only real main difference between level D & C Simulators are that you are required to run more tests, but these are Motion and Sound related, not the Controls
Then of course there are differences between level C & B, which I’m not going to go into
Just to complicate matters, Control Loading systems can be classed either as Primary Control Loading systems (yoke, wheel, rudder etc) as well as Secondary ones (toe brakes, auto throttle etc).
Hope that’s of some help