The most overused term in the Hydraulic world is “oddball sized”, basically that means “I don’t want t mess with your stuff, because there isn’t enough money in it” Unless.... your willing to pay $15-25 for a seal that costs a buck or two depending to how many your buying. I get it, I know the cost associated with maintaining a large selection of seals, deciding which ones will sell and which ones will exceed there shelf life. When your talking about a $50 dollar item, how many people are going to invest >50% of item in parts, plus your time to repair it... it’s tough to balance as a business.
@OP, if your jack is leaking, tear it down and find out why and what you need. It’s unlikely that you will find a replacement in one of the generic Oring kits, as they too are generic in general. It’s also not cost effective to buy from the major seal suppliers, as they cater to professionals, but there are much cheaper options including “The Oring store” who will cater to smaller markets. If you have a implement dealer in your area, they sometimes carry a wide selection of seals/Orings, just take your parts with you to match up. Unfortunately, when dealing with some of the cheaper lift equipment, the QC and or tolerances make it difficult re-seal without thinking outside the box.