Major change for 1966 is the disappearance of the hidden rivets from the back pocket, to be replaced with bar tacks. You can see black nylon stitching on the top edges of the pockets. The guarantee has gone from the leather-like patch, arcuate is shallower, and the fit is slimmer, with a lower rise than the 1955. This is the first more fitted 501, much less boxy than any of its predecessors - what's sometimes called a 'carrot shape', legs tapered, with a snugger fit around the bum.

Features:

Pockets: 5 pockets, back pockets are squarer, bar-tacked rather than riveted with black nylon thread visible; the lines of stitching around the margins are almost parallel. (The watch pocket, too, is squarer than its predecessor, and set slightly lower.)

Rivets: late style, with rounded tops

Belt Patch: leather-like, no 'every garment guaranteed' legend. Model code on patch changes from 501XX to 501 (the 501 0117 appears in the late 60s).

Arcuates: double needle. The LVC version is shallow, somewhat exaggerating the shape of the original.

Cut of LVC version:  “Carrot” shape, with a lower rise than any predecessors. Slim, almost exactly as slim as the 1947, perhaps slightly wider in the thigh and tapering to the same hem width, with a more fitted seat than earlier jeans.

How to size: for an authentic, 60s fit, I would wear these actual waist size, and stretch the waist after washing (or wear them in the bath). The thighs are cut reasonably generously, especially compared to the 1947, so they won’t be too tight.

Note the very square pocket shape, which is characteristic of jeans from 1966 to 1969 or so. Thanks to Rob for the photo.

This is a pair of original 502 (the zipper fly version). Note the very square watch pocket and the lovely lemon yellow stitching. Stitching colour varied from factory to factory. The ‘V’ stitch by the fly button disappears around 1969, at which time the thread changes to a darker, copper colour, probably using poly cotton thread.

501 model guide • 1880 Nevada •  1880 XX • ‘First Blue Jean’ • 1890  • 1901 • 1915 • 1922 201 • 1933  • 1937 • 1944 • 1947 • 1955 • 1966 • 1978 •