For the most part, nobody I know has kept theirs since the 70's. Most of the guys retired, and only wrench on what they currently have, and several worked in my part time shop, and are trusted with the shop tools (including the starter wrench). Most of them are old enough, they don't want to lay down and do it (early 70's the average).
I picked up a Snap~On, with another tool, for less then buying the loose Craftsman one. So I keep it in my home box, just in case. It will probably end up out at my brothers farm.
I believe there was another size that might be good for the tractor, but I don't know yet.