My name is kevin bailey and this is my first post. I have a walker floor jack that I would like some info on if possible. The metal tag on it says J-122, range 3-3/4 tons-3000lbs,and it also has ESA on the tag. I am pretty sure that's what it says as the tag is quite worn. I have had the jack for 30 years or so , and the man I got it from had it for another 20 years at least. I need to put a kit in it if I can find one, but would appreciate any history on it as it was one fine jack. Thanks very much!
I expect 50 years old isn't out of the Realm of possibilities, The Hydraulic design has been around for a long.. long time with only subtle changes throughout the years and the core design is still used on the "Current" HW Lineup of HW93642/652 Jacks, Although Not interchangeable between frame designs. Lots of Suppliers selling kits, Ive presently "temporarily" stepped away from selling kits mainly because Ive found myself with very little free time as of late, so check with Marc's website which is linked above, Maybe google to see comparable prices, Be leary of anything on ebay in Original Walker packaging as these are OLD STOCK KITS and you don't want the headaches as some of the parts wouldn't be suitable for Re-sealing a jack. <-- Although they will have the "Rebuilt with Walker Parts" kick *** foil sticker inside.

A couple words of advice, Tear down and inspect your jack prior to buying a kit, Anything that old can and does have problems on occasion and it might need some machining, Very Common... especially if a jack sits dry for extended periods of time. Secondly.. It will have the Spanner tank nut, It will require some force to remove and you will need to make a special tool to fit the grooves, Don't beat on it with a Hammer, Pipe wrench = NO good, you will only ruin the part.
Here is a tutorial where a Member here detailed his journey with a 93632 which is very similar to your model and blows those exploded view diagrams out of the water. Also.. before I forget, If your jack has the Rear wing style casters (should have), And the caster assembly is bad... They are pricey. The Wheels are replaceable but the Caster assembly if required takes a specialty stem type and are $60+ for each side last time I looked. I know in the past ive rebuilt the Assembly, which requires some Stake removal, careful disassembly of the lower/upper races and bearing replacement and have good luck, but its a Job.
Hope all this information helps... Welcome to GJ.