You are probably looking at the "Pancake" power pack type cylinder.
The LR kit comprises of what I believe to be the standard Sykes Pickavant 10 ton hand operated ram which is used on their range of hydraulic bearing pullers.
As you know, the ball joints are usually siezed in and the exposed part of the body rusty as hell. The extractor I have made is constructed of D2 tool steel with 4 tie rods secured by high tensile bolts. The main drawbolt is 3/4" UNF high tensile.
I have no intention of attempting to push them out cold, the axle yokes are built like a brick sh*thouse an I would use plenty of heat to assist with removal, after all the old one's are scrap. My experience of P38 wheel bearing replacement is that when the bores are polished and lightly oiled, the new joints will go in a lot easier