Does anyone know a simple way to measure differential preload?
I have an uprated 7.5-inch diff, it was really really good in the car, locked really well - only changing to a supra diff because of a higher power (a bit of a shame to be honest)

The diff has 240nm written on it, and I know it was rebuilt when the previous owner had it but the paperwork is long gone. Everything points to it being a 240nm spec diff, which holds a lot more value than a standard differential - but if there’s a simple way to show a buyer this is the case It’ll make life easier than a verbal promise of “it’s really really good honest"

Thanks for the help!