I rebuilt power steering box in my 68. All seals, piston rings and main bearings. This re- build kit was available from my old fashioned local auto parts store. There were a couple of challenges. I he first was devising a wrench to be able to unscrew gear shaft retaining nut and then finding a small enough pull scale to check the worm shaft side play and the center bearing pre- load. It if the side play would have been too much in the worm shaft I may have been screwed as you are supposed to replace the assembly. Not sue if that is available. I haven't touched a manual gearbox, but worn teeth on the cross shaft or ball nut could be a challenge.