I bought a new Duluth Pack # 3 for $30 in the spring of 1969, I still have it, I still use it, all the time. It is no longer olive drab, sunlight and rain have turned it a nice soft gray patina. I oil the straps on a regular basis and I've only replaced one of the closing straps, as it just plain wore out. When I moved to Alaska everything I owned, fit inside it. It has rode on my back, in canoes, jeeps, dog sleds, super cubs and other bush planes all over the northern hemisphere. It stuffs, loaded or empty into available spaces nicely. Thursday, I put berry buckets, lunch, coffee pot in it for a long day of picking lingon berries (also called low bush or mountain cranberries up here). Whenever I travel I use it for luggage, airline baggage handlers have not damaged it in anyway (yet). The folks I met in Sweden and Norway really liked the idea of a huge sack that you could live out of. They are not the greatest thing for backpacking, although, the spring I trapped beavers I carried it many, many miles every day in thick brush that would have not have been possible with the frame packs of those days. I've tried to replace it with a #4 but, didn't like it as well, I am enamored by the Woods Packs especially the 200 with the attached axe sheath, but have never seen one yet. Last fall I bought a #2 Duluth pack that is roughly the same vintage as my old #3 it looks like it went on one trip and was stored in a closet for 45 years or so. I plan on using it when I get older, more frail and can no longer lift a full #3.
I think in the 90's time frame, Duluth Pack was sold to some bigger company. Most of the employee's didn't like the new management team, so they quit. Some of them then started Frost River Pack Company. I think if I were in the market for a new pack that is where I would spend my money. I'm pretty sure their backs are made to the old high standards and with some care will last nearly 50 years also.
I have a friend that goes into all the thrift stores and buys Pataguchie stuff. He takes off the label and sews them to some of his rugged work clothing to make his own fashion statement. He gets some strange look from the people that have never seen that particular item in the catalog.
Another friend cuts off all labels on his high end gear, claims that he isn't going to advertise for some companies gear unless they pay him for doing so. When I visit him, I get a mug of coffee set on one of those leather Duluth Pack logo patches for a coaster.