1970's Vintage Underwear - Men's Small Size Sears Blue Nylon Brief

I believe these are sears because they look identical to the underwear in the catalogue.

4 NOS Vintage Jockey Life Underwear Boxer Shorts Tape… - Gem

Sears Underwear & Socks for Men - Poshmark

Мужское нижнее белье Sears - огромный выбор по лучшим ценам

A few best of the worst 1970s men's underwear catalog ads. : r/vintageads

70s Men's Briefs

Las mejores ofertas en Calzoncillos para Hombre Sears

70s Men's Briefs

Mens Vintage Nylon Briefs

PHOTOS: 25 vintage male underwear ads & a brief history on undies - Queerty