I have always been a bit sceptical when people post that they bought springs but they sagged after a while, as every time I have checked mine the free length has been to spec, which is the only real way to check.
However I have been noticing that my 92 RRC seemed down on one (RHF )corner.
As I was fitting new Bilsteins after my Flinders/Strezlecki trip, I thought would go the extra mile and check the spring lengths.

My RHF was about 20-22 MM shorter than spec while the LHF was OK. It is/was a "blue" LRA spring which should be about 15.5-15.75 inches long. The RH front was down about that much even with the stab bar evening it up.
I had anoher set of "blue" springs so I fitted them, only later realising they are stock fronts. Ah well my next trip is a big one with the camper on, and that will raise the front a bit.
I am not sure of the wisdom of fitting one new spring, even if the other is still on spec.
Regards Philip A