First off, where did you get this one from? Assuming it's from a catalog
parts dealer, which actually shouldn't be at fault. These guys are order-processors. They get cores, send them to a place that rebuilds them, and keeps a stock of rebuilt units on the shelf for those who place orders.
What you should try to find out is who REBUILDS them. Somewhere in this world is a shop, I'm sure more than one, that spends their days rebuilding steering units. Their customers are catalog stores, auto
parts stores, and in many cases, individual buyers. If you can find one of these shops, give them a call or visit and talk to the fellow who actually has his hands inside, cleaning it up and installing the new gaskets.
Case in point: I had a problem with my 1964
power brake booster. The
shop manual details how to rebuild it, but good luck -- you can't find the
parts. I did, out of used boosters. It worked for years, until one day the
master cylinder began leaking. Next step, replace both with a rebuilt cylinder/booster assembly. Fixed the issue at hand, but I hated the feel of the brakes. Yet another, and another, booster didn't help. Out of frustration I began searching the internet for "
brake booster rebuild" shops. Found one in Ft. Lauderdale, which took mine and nit-picked it over to ensure it's perfect. This story is more complicated -- had other issues as well, but today the brakes are great, and this fellow's assistance went a long way toward getting me there.
If you can find a shop that rebuilds these steering units, talk to them first and let them know about your problem. Maybe they can take your boxes in trade for a good one, or rebuild one of them with some case
parts off the shelf, or whatever. If the same case is bad on both, maybe good cases are in short supply and there's a workaround -- or they can find a good case for a higher price, but at least they can fix it. You'll save money two ways -- first, no dealer markup. second, whatever the cost or requirement, your specific problem will be addressed personally.