If you're looking for the old-fashioned style Levi 501 jeans like the ones you bought in the 1970's or 80's, that are made of heavy denim and you bought them oversize and washed them hot to shrink them to size, at least one of the ones listed on this page is the right one: the Color: Rigid STF (at the moment it is the color at the far left).
It took many hours of searching and researching (researching blue jeans!) at several online stores and non-store websites to determine whether equivalents to my old ones were even made anymore, and if so, which ones they were. Levi calls countless styles Classic or Classic Fit, and countless others Original, and the 501 number was apparently successful, so they call a lot of them 501, too, to the point where these adjectives and style number have no meaning anymore. Classic and Original probably just mean they're Levi-Strauss, and 501 is meant to catch your eye. Maybe they hope you'll make lots of mistakes and have to buy lots of jeans while hoping to find the right ones. If it sounds like I'm joking about that, I'm not.
So it was with some relief that I got these, saw that they're the right style, shrank them down, and they're fine. There is even an improvement over the old ones: the button-fly holes are now are reinforced with stitching, which they didn't used to be. Mine say Made in Haiti; quality seems just fine. The denim is heavy-weight.
If you're looking for the type of old-fashioned plain style jeans that I described, the keywords to look for are: Rigid, Indigo, Shrink-To-Fit/STF, Straight Leg, Button-Fly, Rivets, and 501 (even though it can mean almost anything). When you're looking at an item description, the more of these keywords are omitted, the more suspicious you can be that you may be looking at an "impostor", possibly even an impostor style made by Levi itself.
Shop carefully. It wasn't an accident that I ended up with the ones I set out to buy. It took more than a day of traversing the Levi-Strauss style minefield.