This is the complete range of hydraulic seals used on the JCB 4CX, complete with their location on the machine, and the serial number ranges they were used on. If you want to find a hydraulic seal kit for your 4CX, it's here.
Using our information below, you should normally be able to find the right ram with just the diameter of the chrome rod and the serial number - without having to remove the cylinder off the machine. There's once instance - the Dipper ram - where you'll have to split the ram and measure the piston bore diameter.
If the seal kit doesn't fit, send it back and we'll refund you.