But it's not the same film. Modern Tri-X (even discounting that there were two Tri-X films for decades, the 400, sold in 35 mm, 120/620, and sheet sizes, and 320, sold in medium and large format only) has much finer grain than the Tri-X I had access to in the 1970s. This is in large part because Kodak reformulated TX when formate doping technology allowed literally doubling the speed of a given size of halide crystals, which was applied to make grain smaller more than to make film faster. The closest film you can buy now to 1970s Tri-X is Double-X Negative cine film, 5322 in 35 mm and other numbers in smaller film (and 120 from Cinestill, who apparently have the resources to order custom cuts and such from Kodak). Shoot Double-X at EI 400, push enough to match that EI, and you've got a film that's remarkably close to old TX -- closer than what's now sold as 400TX.