I have a pair of hoist cylinders with two telescopes on them. They came off of a mid 60's two ton grain bed. I was thinking about rebuilding them but see no way to take them apart. Is there a chance you would have to cut the bottom off and bring the cylinders out that way. I pulled the screw on cover and wiper seal off and there is a steel ring that looks like its part of the cylinder under the dirt wiper seal. I did air pressure one of them and had no leaks so they might be ok. Might hook up a 12 volt pump and put real pressure to them before making all the brackets to mount them.
Pictures help as there are different designs. That said if it's like many of them if you take out the wiper (outer most seal) you will see a brass adjustment ring. Look closely and you will see some small holes in the face, it takes a special spanner to remove them. By the way the spanners get quite costly if this is the design you have.