Hi Jean, If using the bottle jack, I found this heavy duty attachment to place on top of the bottle jack in order to jack up the Grenadier from it's axles. It's called a "Bottle Jack Budy". There are 2 versions,
one for a smaller radius axle and one for a larger radius axle, which perhaps the Grenadier has.
This link is if for the one that would fit a larger radius axle, which may fit both axle sizes. Looks like something to add the the ever growing list of things to buy. DaBull
https://bottlejackbuddy.net/the-big-one-1