The 501 shrink-to-fit, button-fly jeans have undergone some radical changes. The pocket socks are shallower and the material thinner. The denim is not as heavy, and the once durable stitching is now a hit and miss operation. The structure of the 501 has changed. Gone are the engineered (7) traditional belt loops, which now number only (5). Only one back-centered belt loop exists now, leaving an 8-inch span between the belt loops on either side. Note pic. The black Levis are from 1997, and the blue Levis are from 2018.

postscript: The black 1997 Levi's (w/ black stitching mind you, not the "Filipino" orange/gold stitching of today's versions) are 33 x 36 and fit perfectly. I just ordered a 501, shrink-to-fit Rigid Blue pair in 34 x34, and as expected, Levi changed their sizing, so if you want them to fit, then order one size larger than normal in the waist, and the next size shorter in length than you would usually order in a 501. They're a little baggie in the seat now, but far from the "marble bagger's" of their size 33 waist offered today. So, waist size up, and length-down and you might be happy. Levi's still are missing the two back belt loops, so cut some off of an old pair and have them sewn-on like I did. Boy Howdy. Hoop jumping to buy Levi's. Sad.